I'd suggest to lease the horse to someone (after seeing him/her riding style and deciding that your horse would benefit from it). And, the horse should stay in a barn that you can visit weekly. Every 2 weeks at top most. There are so many horror stories, when you give your horse to someone who should care for him, and then you find the horse... starved, manhandled, scared to death of things that he didn't mind before, having untreated conditions (worms, cuts, whatever), being ridden with open wounds on the back from an ill fitting saddle, oozing pus from the sides from spurs or a bleeding mouth from an harsh bit and harsher hands; being kept in his feces for days, being ridden so hard he's dead lame, being shoed incorrectly and then ridden too hard... nope, don't do it.
Find a compromise where you can go anytime and see firsthand that the horse is still healthy and well cared for and well ridden. If your horse starts losing weight, or acting scared or sick, or if he has visible welts from being beaten, you should be able to notice in time, not 9 months afterwards.