. I am putting in the middle of a long range vision of a permaculture food forest garden, and have had my back go out 4 times since the beginning of it...hardscaping stonework, weeding, and shoveling woodchips did me in.
Just a couple ideas. This depends on the size of your plot...and possibly your age...and how much money/help you can get or put into it.
If you have a smaller plot or even just more specifically in zone 1: You might want to consider a modified permaculture system that relies on raised bed planters with a wide ledge around them for working comfortably while sitting. A low maintenance path around said planters would also be a boon.
Other ideas- keep fruit trees to dwarf size, and prune them so the branches angle more down for ease of picking. Mulch, mulch, and more mulch! Weeding is the bane of a bad back. Keep your focus lower with vines that you plan on harvesting from also. I know this means losing part of your vertical space, but if you can't garden because you strained your back on the ladder while getting grapes or apples...well...it's all about trade-off isn't it? If you want to get woodchips for mulch, buying them bagged is a better option for the back than shoveling them into a wheelbarrow...same for dirt or compost...if you have to buy it.
Minimizing work that requires bending/twisting motions with the back is key. Like an earlier poster said about knees for lifting...
A permaculture garden with a touchy back is totally doable...but might need a bit of a different focus. Hope it goes well for you!