Car camping mattress options

I use a Therm-A-Rest and especially since I usually end up sleeping in a sack on top of my sleeping bag, its very comfy.

Pro-tip: recline the front passenger's seat BACK, not forward, and use a board for under the mattress. That gives you about nine feet to stretch out from glove box to tail gate.

 

"...I'm looking for a decent foam option that won't break the bank."

Have a look at this: Custom Bed build: https://youtu.be/a_83eRuOhmU

He has many other camping/living in a Prius vids and ideas on his YouTube channel...

 

We used some backpacking mattresses that have a foam layer sandwich but are also inflated so that the two think foam layers are about 1” apart when fully inflated. We used them on top of about a 2” foam matress topper that covered the platform in the rear formed by removing the rear seat headrests, folding the seats flat, and inserting a small plywood board between the front edge of the folded-down rear seats and the back of the front seats. The advantage of the separate top backpacking mattresses was that we could each inflate our mattress to achieve the desired firmness to support different body weights between my spouse and myself. I am 6’2”, so I was on passenger side while the much shorter spouse was on the driver’s side.
Have fun!