If you put mobile homes on a lot, you need to have water, electricity and septic (or sewer connection). 

I'm looking for your typical double wide or smaller house on a little plot of land with hopefully city water and no land or HOA fees.

A water line burst over the winter while we were away and we are stuck with a bill of 3500.

One of the houses had a active water leak with kitchen sink day 2 of my ownership. 

The garage itself is pretty dilapidated--old water damaged doors, a new roof, but many ad hoc repairs and some signs of rot.

Rates have bumped up slightly over the past month so you're likely in the 4s no matter what at this point on a pure investment property (not primary residence), but big picture still a great time to use leverage with historically low rates, and to mitigate your exposure to the crazy amounts of inflation we are going to see over the next few years. 

I had an incident where the pipes froze and the tenants didn't have any hot water. 

I requested the seller fix the roof repairs (small fix), bathroom faucet leak, replace water heater (really old), and replace ac/furnace unit (old as well).There’s about 5 smaller things that I said I would fix. 

. - There are currently 22 full hookup lots (water, electric, and sewage) and a duplex stick built house.- Original RV park was started in 2008.

Water and foundation issues are a big concern in some parts of Sioux Falls.