NAV DVD 7.1 data / 4.2 loader - no joy

I have a 2005 Prius with a 4.2 NAV DVD and Coastal's Lockpick 1 (the button-pusher that activates the software override in the NAV system). I wished to create a hybrid NAV DVD using the new 7.1 data and the older LOADING.KWI software, so my Lockpick would still work. I cannot get the resulting disc to work correctly, and am beginning to think it is not possible. All my attempts will load and show the map and track my current position - they will even create routes between stored points - but I absolutely CANNOT search for an address or POI, because the system just does not respond. I push the address button, and nothing happens.

I have carefully followed the recipes posted here and in other forums that worked for creating a 5.1/6.0 hybrid disc. (Make an ISO of the new disc with Winimage, Inject the old LOADING.KWI file, burn with booktype set to DVD-ROM...) I have made and used copies of the 4.2 disc and it works perfectly, so I no longer suspect my media or burning technique.

As I examine the 7.1 disc, I see several interesting things that make me think Toyota changed the file formats.
Although the 7.1 LOADING.KWI file is the same size (51,010 K, the root directory contains a new file called "05.CMP" (CMP for Compression?) which references the IDX files.
The ALLDATA.KWI file is much larger than before.
The IDX files are all much smaller than on the 4.2 disc, even though the bitmaps of coverage show much larger coverage in my area.
The net size of the entire disc is less than for 4.2 despite increased coverage.

If I'm right that the address data is compressed in a new format, then the days of using old loaders with new data are over, at least for me. If ANYBODY out there has successfully made a Gen4 hybrid disc that works completely with the 7.1 data and an older loader, please let me know. Otherwise I'll have to put my Lockpick up on Ebay

 

A straight copy of 4.2 works perfectly. A straight copy of 7.1 works perfectly, except the override is gone.

The hybrid 4.2 loader/7.1 data disc will display and scroll a 7.1 map, but any attempt to enter an address or POI just seems to hang, like I didn't touch the screen at all - or it returns an "error reading disc" message after a long delay. The inability to enter an address or POI is the same whether the vehicle is moving or stopped. It WILL plot a route to a POI that I saved using the prior disc.

I'm pretty confident that my "error reading disc" is not a disc defect - I've scanned them and CRC'ed them without error in multiple different drives, and as stated my straight copies on the same media work perfectly.