I don't have many details other than it's 11 acres with a future road through planned. 

Prior to this, he had told me that he was going to be late on rent due to something else, well, he finally paid the full rent and late fee on July 12th, but I am not sure what should I do next.

Just remember though as Jay already mentioned, there's a requirement to live in the property for at least 1 year so ensure that this aligns with your plans.

I know I can acquire them, get them running well, and SBA 504 refinance them in 3 years.

Only problem I’m having is i wouldn’t own the land it’s in a mobile home park but there are other mobile homes for rent in there as well.

Many 401k plans offer a loan option for a real estate purchase if you plan to live in it. 

We have had quite a few rental units enter the market in Grand Rapids recently as well.  

Whenever we aren’t doing events, the plan is to run it as a campground on Hipcamp.

Pros could be: Clean water + tub for each guest; on a well, so no water waste concern; can make it design-y + cute; can be used winter (hot water) + summer (cool water); goes better with forest location of the home than a traditional hot tub might; will hold same number of guests as hot tub would (2 people in each tub).In researching I have seen some people on Airbnb have these checked in amenities as 'hot tub', some 'private hot tub'.

It will ultimately be based on the supply and demand of the area but you have to keep an eye on the total renter pool as well.