I suppose it all depends on what the folk you're renting from will allow...and how many trees there are..as in perhaps way more than you could ever use anyway? If so i'd be brutal - rip out the duds for space and ventilation and a heavy reinvigorating autumn prune on the rest. If you need a huge amount of apples next year then perhaps just heavily prune half and see how they get on before doing the rest.
many many moons ago .. (about 50years).. a neighbour was selling his land.. My dad liked one of his old apple trees and we pruned it back just to a few stubs of branches, cut around the base .. roots and all.. and moved the thing to our garden. It took fine and was a brilliant tree until this year finally succumbing to a storm. Even then if I didn't live so far from my parents place it might have been pruned and replanted after some years of neglect (dad died 20yrs ago and mum is 97..so not much into garden maintenance).