Who is going to remove this mini golf course when the tenant moves? And who is going to pay for it's removal? You should have had the tenant put the request in writing explaining the entire request, and then took some time to check it out, to see if it requires a permit to build? Can it be installed without violating the local ordinances? Will it affect your neighbors drainage, will it have lights, noise, moving parts, water hazards? You did not do your home work on this!