Stealth Camping: Perforated Vinyl Rear Window Inserts.

After a few abortive attempts, I finally completed the rear window perforated vinyl inserts for my Prius camper. See attached photos.

These are fabricated from 30 mil PETG with perforated vinyl applied to the outside surface and 20% ceramic tint applied to the inside surface.

One unanticipated benefit from using perforated vinyl is that, behind 35% tinted glass, it roughly matches the appearance of the front windows (50% tint but w/o inserts). The end result is that the stealth windows are not noticeable from distances greater than 30 ft.

50% 35% 35% window tinting was already installed in my vehicle (per local DOT regulation) prior to installation of the window inserts, so the overall tinting for the rear windows is 20% (insert) of 35% (rear window) = 7% from tinting, or 93% overall attenuation due to tinting. Add to this roughly 60% attenuation from the perforated vinyl (the equivalent of 40% tint) yields roughly the equivalent of 3% window tint (97% overall attenuation).

Last photo is with perforated vinyl inserts removed.

Work remaining: Hatch window inserts - to be completed by the end of January.

 

My vehicle windows were already tinted so I would have had to install the perforated vinyl to the vehicle window exterior. That would have attracted too much attention, and probably would have been in violation of local DOT regulations (installing BOTH window tint and perforated vinyl). Instead, I opted to build my own PETG inserts and apply the perforated vinyl to the cut-to-fit PETG inserts... ...with some extra tinting on the other side just for sh*ts and giggles. As it turns out, this was the best possible configurations for a vehicle that had already been tinted. As you can see in the photos, having a tinted reflective surface exterior to the perforated vinyl makes for excellent stealth optical effects.

Believe or not, most of my time was spent cutting paper dolls (dummy paper inserts, and later thin cardboard inserts) refining the window shapes until I could get it to fit without too much trouble. The cardboard templates have flexibility similar to 30 mil PETG which is necessary to form-fit test. Once I got my final cardboard templates, I used them to trace out the shapes on the PETG sheet. I then cut out the shapes with heavy duty kitchen scissors. It is extremely dangerous to use a blade to cut PETG. Though it is quicker, it takes 3 swipes to cut through the plastic, which is an accident waiting to happen (I sliced off the edge of my left index finger with a box cutter, attempting this). Some addition trimming of the cut PETG shapes is required after the initial form has been cut out.

Applying the perforated vinyl on a horizontal piece of plastic was problematic, and I would often tear the vinyl and have to start over. The solution to this was to spray the PETG surface and vinyl adhesive (black) surface with isopropyl alcohol which temporarily cut the adhesive so that you could easily pull up the vinyl off the surface to correct mistakes without applying too much stress. After getting all the wrinkles out, I re-activated the adhesive by spraying the surface with distilled water, diluting the isopropyl and then soaking it up with a microfiber towel (repeating the process three times to get all the isopropyl out). Once all the alcohol was removed and the surface was dry, the adhesive would be back to 100%. The tint film was applied on the other side of the PETG as you normally would (isopropyl was not required)

The answer to your last question is "yes". The PETG sheet has to be very flexible so you can bend the inserts to pop them into the window recesses. The 30 mil PETG sheet is perfect for this - it comes in a roll.

Flat black 3/8" pinstripe was used to seal the laminate insert edges - applied on both sides of the PETG to provide a ~3/16" light seal around the insert periphery. The reason why I chose pinstripe was that it was forgiving when pulled off during fit testing and could be easily re-applied. Once final alterations are completed and fit verified, I will fix the pinstripe with a stronger adhesive (probably super-glue).

I used gorilla tape from a local hardware store, for the insert pull tabs. These need to be applied to the edge of the insert before applying the pinstripe (otherwise the gorilla tape will just pull the pinstripe off).

I purchase all of the required materials on ebay as follows:


30 mil clear PETG sheet, 48" x 96" sheet - 1 roll

Perforated One Way Vision Vinyl, 48" x 60" - 1 roll

Car Solar Tint Nano Ceramic Tint Film, 60" x 120", VLT20% film - 1 roll

Matte Black Roll Vinyl Pinstriping Pin Stripe, 3/8" x 32 ft roll - 4 roll

 

Clear PETG is transparent. And with perforated vinyl, it has one-way-mirror qualities for privacy during the daytime. For night, I fabricated covers out of 1/8" black foam board - similar to your twinwall, except less flexible. I fixed the flexibility problem by cutting the foam board inserts in half and put them together again with gorilla tape, so that they could be folded to install. At night, once all interior lights are out, I can remove the foam board covers so that I can once again see out though PETG and perforated vinyl, and still have privacy. Just like a one way mirror, the only time you lose privacy is when an interior light is on. As long as there is more light outside the vehicle than there is inside the vehicle, privacy is maintained.

 

AVS 894055 low profile vent guards - fits 2018 Prius hatchback. I got mine from eBay, seller: auto_connection for $57. However, I believe auto_connection no longer provides this item, so I have provided an ebay link to a different seller. Also, you will need to shop around to get the AVS part number that fits your vehicle. AVS 894055 fits the 2018 Prius Prime, but is listed as incompatible with the 2020 Prius Prime baseline 4D hatchback (I don't know if it fits other 2020 trims).

There are (or were) a lot of bad review for AVS vent guards that cited the product as heavily scratched upon receipt. I decided to chance it and ordered a set back in August. Sure enough, upon receipt mine appeared to be heavily scratched too. Upon closer examination, however, I found that the scratch marks were on the vacuum seal / shrink wrap packaging and not on the product itself. Needless to say, I was glad that I had taken the chance and opened the packaging to inspect, as I have been very pleased with this AVS product ever since. They're perfect for the 2018 Prius Hatchback.

 

Typo correction: My "300 mil PETG" should read "30 mil PETG" (now corrected)...

...Big difference.