I’d like to keep the current fixed-rate mortgage in place and, if possible, have the debt transferred to the LLC as well.

There's micro neighborhoods that do very well, even in a macro declining population.

A tenant living in a 100 year old called board of health for drafting windows (never called us first) and BOH made us replace them within 30 days, well custom windows take longer than that to make so we got fined.

I am no expert and just do what I am told.  

RE is always changing and if you have only one niche then well your limited in opportunities and subject to the conditions that exist at the time for that strategy.  

Well, the original close date was delayed with no concessions. 

I'm in Phoenix as well, started out house hacking and have helped out a few other clients to do the same. 

I still have contacts in NARPM as well as more than a few Property Managers.

If I am hell bent on renting by the room (I don't think that is a good LONG-TERM strategy, will elaborate later), I can do that on both sides of my duplex as well.  

Well worth the money.