rear seatbacks removed, no higher than rear cargo area?

I'm trying to design a solution to get my e-trike (GreenSpeed Magnum about to have a motor mod) into the rear cargo area of my 2021 Prius Limited.

Being old and disabled, I'm thinking of folding it into a bin I slide up a pet ramp. The folded length and width will work, but the height of 28" won't because the rear seatbacks are a few inched higher than the rear cargo area, which itself only has the 28" of height. (Folded length 39"x32" width.) Hence my question: With rear seatbacks removed will it be no higher than the rear cargo area?

Unfolded I find I need to remove the quick-release front wheels for it to fit diagonally (though the front passenger seat was not usable), and I don't know how to get it in there unfolded without hurting my back like I did last time. (Unfolded 78"x32"24/28".)