Courts routinely tell Condo HOA's that they can designate building as non rental building.The idea that a HOA tels you that you cannotI look for properties where the HOA fee is no more that 8-10% of expected rent and expense it off for what it is Pre-Paid Maintenance and Capital Improvements.

All the probate issues are up to the trustee to work out.

Thank you @Lawrence ZhouWill start looking into those areas.If things work out perhaps we can help each other out with challenges and questions down the road.I am in construction management (electrical construction specifically).If there is anything that I could help you figure out let me know.

Let's also assume the room is always genuinely locked and I'll have a reasonable way to argue this, e.g. something beyond "it should have been locked".My thoughts:1) It's a locked door, literally no one will know there's a gym on the other side2) Worst case is that someone broke in, worked out or claimed to work out, and filed a lawsuit saying they used the home gym and injured themselfIf I have evidence the person broke into the room (e.g. video from the inside of them breaking the door/lock), would I still be realistically liable?

Though, if there's not I'm not sure how that would work out in the long run. 

In my experience, an amicable mutual termination of a lease can often work out in the landlord's favor. 

That'll take the guess work out of it when you receive applications and make decisions like this so much easier because applicants will either meet your criteria or they won't.

I'll let you know if the current lot I'm focused on doesn't work out.

From you POV, is it ethical to work with multiple agents at the same time or it's better to select one and "fire" them if it doesn't work out after a certain amount of weeks/months?

If you're going the umbrella insurance route, make sure it will cover you for several things including just the routine slip and fall (like mold or earthquake).