Now for the house you are leaving behind…I like to have this one freshly painted, and take action on any maintenance items.  

I'd consider doing some kind of cash out refi on the property at a number you're both comfortable pulling out, while still leaving $ for reserves to maintain the STR you currently have.

There are other concerns with this approach, but 50% down on a ready to go $150k rental in a cheaper area?

I can't speak to that myself, it's not my specialty but I think that would be one of your biggest concerns is their permit processes. 

If prospects upload ID, pass a quick background check, and maybe upload a pre-approval letter, I think that answers both the security and tire-kicker concerns. 

If the tenants leave cereal boxes out and the house gets overrun with ants, it's still your responsibility as the landlord to have pest control in place to prevent or treat the problem.

If you’re still concerned, you could consider installing programmable thermostats or low-flow fixtures to help control costs without relying entirely on tenant behavior. 

do more research and make sure the property will cash flow when you leave.

@Truong Vu You have some valid concerns, but most investments, whether for your personal use or long term holding property is usually about leveraging what you have.

I have not looked at apartments, but the condos I have researched have a minimum 30-day lease requirement, so be aware of that.One concern I have with short-term rentals is that they are dependent upon tourism.