So- in your approach, I would not mention that at all.

He kept mentioning he can sell this today about 5 times during the visit. 

Also you mention he has an awful reputation yet you acknowledged in your initial post you repeatedly buy properties his brokerage represents...not quite adding up.

Do a series with each focused on the different things you mentioned. 

@Darrell Overly  there are certainly enough mobile homes in the area around phoenix (East Mesa/Apache juction) but your issue may be the age of the homes and any limitations the park has on renting.   

As @Bradley Buxton mentioned, you can make many markets work! 

Its the less aggressive model but it was programed into me from a young age, keep your business risk separate from the things that you need to live (home, car, food, etc.). 

As others mentioned, not a big deal for the solo 401k itself to lend.

Sorry to hear about this.You mentioned that the tenants haven't moved in...how long has it been vacant for?

Funny that you mention a Top Golf because part of this saga I didn't mention is that at one point the developer who was failing at rezoning this site was "threatening" to open up a Top Golf on this parcel smack dab in the middle of the city.