i could do with renting a chair for a while to see how it works. the berlingo type vehicle may appeal, wont have to lift too high which is a major appeal given the lower back issues. and the drivers seat pretty much where i am.
i may look at something like the qashqai it being a bit longer than the juke a chair may fit behind the drivers seat which would be less height to lift.
kezo i think the chairs i am looking at will do exactly what your suggesting sat up against the back seats maybe secured with a bungee. the only thing i am a bit worried about short of getting a hoist is getting it up and in the back aint great at the moment. the jukes boot is fine it has the flat load thingy that you can drop to gain height but at the cost of loading over a lip. but the space behind rivers seat isnt great. as you say it would be jst me and the chair so something lower and smaller with the back seats down would be doable. wheres the suzuki jimny when its needed lol.