He's looking for mid-teen returns open to either value-add or ground-up development deals. 

It can take a while to get traction for mid-terms on listing sites so as long as you give yourself a buffer between when it will close and when the tenant will move in I think you should do it. 

If that's where you're running into a problem then I suggest looking into the travel nurse/tech scene for mid-term rentals. 

The key is to know your audience for mid-term rentals which can be traveling professionals, traveling nurses, people moving to the market, etc. 

Does anyone want to rent their ADU or detached guest house to me for mid-term rentals?

Knowing how design, architecture and entitlements work represents formidable pieces of the development process and gives you an enormous leg up in entering the development industry.The "$$ side" of commercial development is nowhere near as complex as what you already know.

For Mid term rentals, I've been offering bi weekly housekeeping service.

The location is GOLD and he uses them for mid term rentals.   

I'm hoping for mid 5% range.

She has 5 kids ( kids have been destroying the house so I did not renew after 2 years )I have new tenant selected for mid April after I fix up the house. ( she is great and I don’t want to miss the opportunity of having this tenant)Current tenant says she hasn’t been able to find a house so she can not leave because she can not be on the street with her 5 kids.