This tenant operates a resale business and is currently renting a single unit on the ground floor.

Think through the scenarios - could you comfortably handle two months of vacancy while needing to replace an appliance & prep the unit before next tenant moves in (> $10k)? 

Would I need to re-write the operating agreement if it was not previously used for real estate?

I.e. if you are great with numbers and an excel wizard, you could likely seek out a "deal" guy, who loves networking and hunting for properties, but doesn't really understand how to translate operations into financial models.

Those sites are a good starting point, but I wouldn't underwrite anything solely based off those estimates.I would suggest Enemy method - Same bed/baths, Amenities offered are step one, but speak to other operators that have similar properties/amenities and compare numbers with them (That is true data not estimates)How well are you marketing and providing guest experience?

There are ~90 locations across the U.S. supporting the day-to-day operations of our construction crews.

Chances are they are a better operator than the turn key providers and are developing better assets but this is something to consider down the line.

If your STR no longer qualifies as an STR and is now operated as an MTR/LTR - I'd say no problem.

Last year we looked at 515 operators and deals and only invested in 11.

I operate in a few markets and two of them are Philadelphia, PA and Reston, VA.