The average bathtub is NOT designed for people...it's designed for space saving and profits, and not yours and mine.
This is my opinion after many decades of wet-testing dozens of tubs.
In my current one, I roll when soaking in a solution, a few minutes at a time on each of four sides. I also slosh with a facecloth on the drying side.
THEN, I try to get out. Hah!
The best way, for me, is face down, one knee up under, and to push with toes curled under on the extended leg. (It's a sight to behold!)
Consider foot soaks!
Maybe some day someone will invent a spray bottle to be attached to a shower head, and recycling shower water!
Those tubs with seats and a watertight door would be great if manufacturers would lower the price and go for volume.
Beyond that, consider building your own tub, made of stones...indoor or out.
There's gotta be a better way!