If you're looking to avoid a rather large tax hit, a 1031 is probably your best bet.  

Based on 45 years in real estate, I’ve experienced these types and I believe they are the biggest time suckers to be avoided as quickly as possible Types of Customers to Avoid1.

So a nicely decked out  cabin I bet would rent real well for STR purposes  Not sure about permits etc..

Trying to go to companies directly is rarely going to be your best bet. 

It looks like networking and meeting people will be my best bet.  

I'm betting your numbers look like mine, and CapEx saving is eating up a lot of it.

Doing this like a brrrr I see as the best bet, for example my property does still have room for improvement adding a bedroom and bath to the primary structure and then the ADU.

The safest bet is to try to get a variance from Union City. though clever, your combined unit lease agreement would likely cause trouble if ever scrutinized by the Tenants or the municipality. 

And that gave us a feeling of security that allowed us to take "riskier" bets.

I think the outskirts are you best bets!