The listing broker is going to try and sell you on paying a price that makes sense given the projected or proforma rental income, a dynamic that is the equivalent of how the listing agent on a SFR might try to sell you on paying a price that bakes in future/anticipated appreciation, or "look at this home's potential!" 

I prefer to NOT work with large banks, looking for small to mid sized direct lenders or mortgage brokers with training.

(I know you're not a lawyer and will eventually seek professional advice.)I just talked to my RE broker and he said with LLCs you typically do commercial loans.

Mortgage brokers: are there commercial lending options that can work without experience?

That would be his issue with his lender.You would have the option of forcing him to complete the deal, he then has to work out the problems between himself and his lender, that is none of your problem or business.Have your attorney or the real estate agent's broker send a strongly worded letter as a warning about the consequences ( a lawsuit he is unlikely to win).

I have been in NNN 20 years investor and principal broker and owner of my company.

With investment and commercial financing most of the time broker and lenders can work and are familiar with all 50 states!

AND… you can roll in your broker fee into the loan amount without affecting your rate, and you can get 6% seller concessions.

A lot of brokers are not even aware of what rental arbitrage is so maybe your broker understood a completely different concept.

Gabe, I would contact an experienced investment loan broker who can help you compare terms across a wide variety of vetted lenders and their platforms.