Don't you have a shed?
No one enjoys having family around for too long. I have a big heart so I'd let him stay for a while BUT, only in the condition that he also looks for another place to sleep by. Kinda like having divorced parents, three nights here, four nights over there. It'll drive you less crazy, urge him more to find a place for himself and if you switch it up a bit (1 night here, 2 nights there, 1 night here, etc) you can make it so that you have almost all the time an eye on him.
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