Welcome to the site.
I agree that the AA5 (half panel) would address your back seat issue, but not many on the used market, and probably none on the rental trade ins, but you will have the same issue finding a used panel as there just not that many out there.
Good luck finding what you want.

 

I'll probably end up with the "normal" window version at this point. Not sure how long my buddy will let me use his spare set of wheels to commute a little over 100 miles a day. I just love the panel version as they remind of my 1960 Chevy panel truck I had about 20 years ago. I'm sure the kids will be happy as they will be able to see out some windows. I'm on to a nice 2008 LT with with 27000 miles. I'm waiting on word from my insurance company on my Kia, then getting a loan with the Kia probably still on my report may be tough.