@xJumperx: Yes. And a free lease can be on or off site. You can include tack (or not), brushes (or not). You can mandate certain levels of care. ALWAYS inspect any facility they are moving the horse to. Google contracts and add stuff in as you need it. Include EVERYTHING in the contract--whether the horse can be shown, trailered, hauled to out-of-state events (or not), barrel trained, endurance ridden, road ridden, shod (or not), cycle of hoof care, vet care, etc...Include the frequency of inspections by you...Once every three months? Six?
I "free leased" my first horse to friends. I told them I'd never ask for him back, but they were forbidden to sell him. He HAD to return to me if they couldn't keep him. I was the last person to ride him before he died, twelve years later. It never crossed their minds to give him up and had treated him so well. It really is a great solution to your specific problem.
The only downside is that at some point, the horse will likely come back to you--older, less useful for active riders--and you'll have to decide what to do with her then. Keep her, put her down, or sell her to questionable people. Still, considering her age and spirit, she may be going actively well into her twenties.