At minimum it will become an added storage area for him and worst case the garage will turn into a body shop where he is repairing his bike and his buddies bikes.If he didn't rent the apartment under the pre-tense of being able to use the garage I wouldn't let him. 

You could have a resort or vacation homes, coffee shop, etc in an area within a mile to the lake.

I slipped up trusted the wrong guy to much he had worked for me over a year, and he ended up falling off the wagon, was taking new tools back to the store for store credit and other fun stuff to pawn shop for cash.. when confronted he admitted it and I reported it to the police.

@Steve Masica,Ok thanks, that's my plan to get the approvals done and then shop it to tract builders.

These quotes came from multiple GCs and 'one-stop shop' firms.

I'm selling the unit, the property, the neighborhood, the coffee shop around the corner.  

So, if a cash flow market is what you seek, then my advice would be to pick one and pack your bags.

Have you consider virtual staging like taking pictures and photo shopping them?

Organize a meet up at a coffee shop to chat and network.  

They have given different short term rentals different amounts of time before they have to close up shop, so to speak.