Just the pure economics of starting/developing a MHP is not beneficial for most people as your hold period will have to be several years without any return...so unless this is okay with you and your okay with developing the land, bringing in roads, water/sewer, electric, cable/internet, developing the pads, and bringing in the homes, your going to be in the whole at least 20k-50k(includes home price) per pad before you even get this up and running to full or close to full occupancy.   

Is this arrangement purely tagging onto Tom's reputation? 

My ultimate goal is to be able to quit my job and have pure financial freedom, so I am naturally drawn to buy and hold investing.

Anything they charge is pure profit.

Eventually, as I got smarter I was able to use conventional financing to buy pure rentals that I never lived in.  

Firing him might mean losing your friend, as she will have to take sides.Friends often expect us to bend over backwards for them, give them more leeway than they'd get from a pure business relationship.I'd be careful with that

In other words, is the appraisal for these types of units based almost purely on comps (similar to how SFH are valued)?  

Purely selfish reasons while on vacation with the family.

So unless you just sold a house in SF, you should start looking farther away from the city for something that makes financial sense and is not pure speculation.

I plan to keep working another 25-30 years until these initial mortgages are all clear, then 1031 the equity to some new, fully paid off properties for pure cash flow, and then retire.