We use private investors and offer them 20% APR, with 10% return guaranteed, paid as a balloon. 

Guaranteed value appreciation or maintenance.Although you said you don’t mind high risk.  

Your money is guaranteed by the bank. 

It's no guarantee but it's a good place to start.

I would have a conversation with the tenant, and then after that if you determine that’s in your best interest and theirs to seek out a new tenant give them plenty of time and make sure you leave amicably because in case you get more rentals and they are looking in the future, I have a higher income that relationship is sure to last, which means that you have guaranteed business in the future.

What guarantees are they making?

While the guarantee of income sounds great, it's only a percentage of the rent, typically up to 70% and the tenant has to pay the remainder.

A smaller valuation would mean less out of pocket to buy out your siblings and lower taxes, but it would also mean the lot rent is a much higher % of valuation.I can almost guarantee you can find properties in Grand Rapids that cashflow because I've found them all over the Midwest. 

Sometimes paying a premium on a home also guarantees a higher demand in the neighborhood and with that may come a higher demand for a rental as well.  

It's no guarantee but it's a good place to start.