Based on your replies, it sounds like the best answer is to keep him at your barn and allow him to be half-leased by someone there. That way you can keep an eye on him, ride him, etc... while still feeling some financial benefit.
For what it's worth, I used to half-lease a horse, which basically meant I could ride 3-4 times per week. I paid half of the horse's board. The owner covered all other expenses--vet bills, farrier, etc. It was a great arrangement for all involved, and it was a pretty good experience overall.
One thing I will suggest though: Whoever leases your horse, please watch him/her ride, and find out exactly what activities your horse will be involved with. Also make sure you approve all tack and equipment that they plan to use. I've seen people do foolish things on leased horses--improper use of draw reins, over jumping, excessive and unnecessary crop/spur use, etc. Hopefully these things would be a non-issue at a barn with good supervision, but I've seen these things happen before. So it's worth considering, and it's why I will never allow someone to lease my horse off-property from where he is boarded.