You can buy single family homes in the Midwest for less than a $100k and have them producing excellent rents.

Are there higher income producing activities that would be a better use and could make you more than what could be $25 a week to cut grass?

If I can get from point A (drawing up plans) to point B (finishing the build and renting the cabin as an STR) I know that this thing will be a cash producing monster with a fantastic ROI.

Real estate is basically income producing gold to fight inflation and in an end of the world scenario you could replace gold with guns/ammo/canned food.

Property manager Oz Realty tried overcharging me for maintenance costs, and refused to produce invoice for any work done.

Some are still producing btw.I won't go into to the tax benefits because your already down that rabbit hole.

As you probably know, water in the basement will start to produce mold in about 24 hours, so your first order of business is to get the basement dry ASAP. 

This amounts to lost opportunity because if you had purchased RE, at the closing it can start producing return. 5) ADUs detract from the existing structure whether this is privacy, a garage, or just yard space. 6) this is related to number 1, but there are many more buyers looking to purchase homes for their family than there are RE investors looking to purchase small unit count properties.

Some states such as Georgia require you be an attorney to conduct real estate signings or have extra licenses such as a title producers license in Maryland to conduct signings.

There's a remote chance that the person who can't afford their payment can somehow afford to relocate the mobile home, but that's a VERY remote chance, offset in part by the higher interest rate, and in part by the surplus revenue received from the low vacancy produced in the park itself.