Swampcat, what kind of soil do you have? And what zone are you in?
For those who have a backhoe, amending an entire mature tree rootbase is not alot of work. While I was doing some window hunting here, I was reading up on how to improve moisture retention in soils. Farmalnd and home are just fine, but my zone 3 sandy soil camp is very sandy. Some spots are organic runoff basins from the hills, some are 6 inches down from the topoil and it looks like you can make a sand castle.
I got rotting piles of fine wood chipper material used to make paper pulp, some are coarse chipper runs for stefanik's plywood mill. They use the material like driveway stone at times to get 18 wheelers in and out of spots.
I was reading you can use manure, compost, woodchips, and peat moss to improve water retention. Also, could spend a few bucks to find larger amount of pearlite or vermiculite. Maybe you can find someone who gets truclokads of that stuff to cut you a deal on a few 55 gallon drums of that stuff.
Dig out a hole, put the top, middle, and deeper middle layer in different piles. Mix in what you have to ammend. I'd fertilize and lime a bit too. Use a portable rortiller to mix it up as you go. Then put it back in the way you found it, deep, mid, then top. Tamp it down some with the bucket, atlest the deep stuff. Probably could do 3 or 4 tree site in an afternoon. Get em ready in the summer, let that fertilizer calm in. Then transplant that fall or next spring.
I told my cousin-in-law he can keep dropping off wood chips. The pile is starting to look like 2 triaxle loads now. Once the ground get frozen here in NY, I will take the kubota and spread most of it on my food plot. Will expand it to a 1/2 acre this spring.
For you rainfall challenged folks down south, I would plant 1 or 2 M111's, Dolgos, Antonovka, Domestic Apple, and Transcendent rootstocks. I wouldn't even graft them, or graft them all the same variety or two. See how they handle drought conditions in your soil.
Swampcat, I got younger trees, but I am pruning them well. Got some pristine, rkansas black, and granny smith if you want to try or give a 2nd take on them.