Eddie,
God Bless you and your wife. I hope her recovery is as full as my wife's from lung cancer.
I'd check with locals, feed stores, sales barn, farrier, saddle maker, riders at rodeos, FFA Chapter, 4H, etc. I'd be on the lookout for the teenaged girl going through what I call "equipause" terrible disease that affects primarily teenage girls. Find the right one to come over & take care of the horses and work with them & in payment she can ride them but she has to do all the "ground work" (getting them used to being handled, feet picked up, stand tied, being led where they may not want to go, no biting) first. Then she can ride. Maybe after seeing her success your wife might actually want to gift her with a horse. Slow but it might work.
I also like the suggestions of hiring the training done. Can you say barter? "I'll give you two untrained, slightly spoiled, papered Quarter Horses" and at the end you give me this one back, finished & ready to ride. Easier to sell finished horses. The problem here is getting the bride on board but she may be receptive to trading two for the new & improved return model.
At three years old they're not too old to learn. I started & finished a 7 year old quarter horse that the nice lady who gave him to me had spoiled horribly. When I got him he had never been shod, haltered or anything other than handed treats, he'd bite & kick and actually charged me ONE time ears laid back & teeth bared like an alligator. Ended up selling him to a fellow with 3 little kids & over the years he showed me pictures of the horse with kids on board. As the kids grew they went from all 3 riding at the same time to having to take turns. God Bless & Good Luck. Wish I was in the vicinity to try to help you out.