I had an inventory of the items along with the lease agreement.

But usually for a tenant occupied it's like $90-120 per monthI've noticed a lot of multi-family buildings are pre-WWII housing inventory - are there restrictions or issues common with that (historic districts, crazy high utility costs, etc)?

Perhaps take a look at:  https://www.loopnet.com/ and see which types of commercial lease listings interest you and from there take inventory of which brokerage and listing agents are prominently features in the space that interests you.

There was no market data indicating there was a market for $3K 3 BR rentals but that was merely because nobody ever supplied the market with the inventory.

She has an excellent tenant profile, but private rental home inventory is low at holiday time.QUESTIONS:Would it be too much to1. locate the owner's email or phone number and then contact them?

You have a contact that has too much inventory.

I'm going to be selling my 2 mobile homes in the next 2-4 years and narrow my inventory to 6 stick built homes. 

Sounds like if I stay conventional then my best rates will no doubt be the 25% down options. 

I do not have a traditional W2 job so I can't pursue the typical conventional loan or a FHA since I don't have income (hence the DSCR route).However, I've seen that most DSCR lenders do not lend if the loan amount is less than $100K.

Great idea, although conventional and FHA renovation loans are somewhat of a pain to qualify for.