But if he came to me with such a plan - essentially gambling with MY retirement - I'd kindly but gently tell him to think of something else.You're asking him to take a HUGE risk on deals you don't even have identified yet - and hope like hell that you can turn 3 deals at $36,000 each in a year.You're just now getting started, so you have NO track record.  

I know students are not always the most gentle tenants but let's assume for a minute that they don't trash the place completely or if they do, they burn it to the ground and the insurance agent writes me a check. 

She was very private about such matters when we were in the service, in fact she never even retorted when my husband and I would poke gentle fun at her for driving a ridiculous hoopty and shopping at thrift stores, but she's definitely getting the last laugh now.$50,000 in five years assumes a private entering at the lowest rank possible and not enjoying any special pays for things such as deployments or Airborne status.

And then, in another twist, we made an arrangement with the builder for my husband to actually be the project manager for the new build on the vacant lot.

I require tenants to notify me asap for any leaks/water damage.)I also had a pretty bad (couple hour) leak from a master bedroom shower (the twist handle exploded off the wall leaving an open pipe and we had to turn off the main water line.)

I don't know what the surface is but if the parking lot develops potholes and someone steps in it (twists their ankle, breaks their leg, etc.) good luck dealing with lawsuit.  

I agree with @Anthony Hurlburt , I would tread carefully here as it could be twisted to appear as an unfair practice by Fair Housing laws.

That showed me he's trying to twist the system and use it against me, because he knows that I gave him notice a week ago.  

There is a twist to this, though.

One solution is a solution for both...refinance.Another solution is a variation of the first solution...with a twist.