So it sounds correct to collect all amounts into my business account then and send a 1099 to the owner reflecting what they received minus the PM fee?

The founder appears to have been involved in businesses outside of real estate: ‘My dream is a locally made grooming products business’ | People | nashvillepost.comSo it does not appear there is a lot of track record there, but those are questions I would ask.

As good as offsetting all his W-2 / Business income?

All contractors (no matter the trade) are businesses, and should be run as such.

But it is my opinion you should try Airbnb, VRBO, booking.com and FlipKey and give it a chance to see if it is adding business.

When the whole covid shutdown occurred, I dropped out of college to help my father's service business maintaining and remodeling residential and commercial buildings.

@Michael Quarles I can honestly say that I've never gotten any solid business from postcards.

Over the past 15+ years in this business, i have seen the good, the bad, and the ugly. 

This is a business.

I'll use these next 20+ years to not only evaluate Real Estate, but other income sources (businesses) to see if I can find something.