The demand for affordable, shared housing is strong here, so filling vacancies shouldn’t be a major concern.

That's great that the bank who currently holds the note wants you on 20 year or 15 year amortization, they view you as a captive customer, they don't have to earn your business any more, as far as they are concerned. 

Now that the 90 day deadline has expired and we haven’t received certified equity nor an update informing note holders of their status, concern is definitely growing. 

I'm strictly concerned with ROI and how it looks to potential buyers.

I am 100% against prenuptial agreements.If someone is concerned about losing their investments, they should be careful who they marry.

Does their ID address match their last rental?

You'll need good contact info for them to be able to collect, and ideally the new address for the tenant however which if you don't have can probably be found easily with some online sleuthing/ contacting their employer, skip tracing software, etc. 

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. 

No email contact address and no one available over the holiday weekend.   

most bankers are standoffish ;-)yes, the HML/PML will be higher cost, but my concern for you is the banker knows he can't do your deal, but will string you along for a while, ask for additional information that takes you time (and maybe cost) to put together and he ends up either ghosting you or taking 6 months to tell you no.I could be wrong and you may be dealing with a "unicorn" banker, but I believe a HML/PML that knows construction in your market will be easier to work with, actually close your deal, and end up "saving" you money in the long-term...just my 3 cents - even inflation has increased this!