I've had my MTR for nearly a year and have had a total of one week of vacancy (Furnishing and cleanings in between). 

put 5k to clean it up and rented out right awayLessons learned?

Additional prior to move-in deposits: Cleaning Deposit $400.

, cleaned, and installed new HVAC, ran all new pex lines/valves/shut offs, all new hardwood flooring and carpet, all new and expanded kitchen cabinets, new appliances, created full bath and connected it to a bedroom to create en suite, repurposed 2 unused rooms (1 into a 4th bedroom/office/playroom and one into a family room, installed new interior and exterior lighting throughout, new automatic garage door, and landscaped.

It needs to be moved cleaned out after the previous tenant. 

For $45/month, you get $5,000 in rental coverage for things like missed rent, excessive damage, excessive cleaning, pet damage, and eviction costs.

Compare that to your offered purchase price and surely it would be more profitable for him to wipe his hands clean and let you take over.

We cleaned it up, sealed any holes we could see and went on with renting it out. 

You can probably find basics of these forms online and then have a local attorney clean them up and make them compliant for your state (or the lawyer could draft them although they'd be a bit more expensive).

Learned about clean out, demo, plumbing, HVAC, electrical, flooring, design, floor plans, functionality of a home, landscaping, and all the nerves and excitement that come with this business!