Knowing that time frame requirement may help you to make more efficient business cash flow projections.Also, if you can be creative to find a solution for people, you can often find great values that are not on the market. 

A part of me, and this very likely could be wishful thinking, has a hard time believing that someone, the city government, the state government, the co-op association, etc isnt going to step in and find a solution for this land lease situation.

The best solution to answer your questions is calling over PM's and find out their rates and terms.Rates:  My limited experience for property management in LA, 6% management fees seem to be average. 

I have spoken to the team at Royal Legal Solutions (@Scott Smith) and I am sure they will give you great advice.Bob

I know partners are also a great solution but it's hard trusting other people especially since i have already been hurt by a business partner before.

If the blip is temporary with business you might could offer a short term solution of reduced base rent and sharing of profit above sales of XX annually.

If not, and this is not in my wheelhouse, but probably a commercial or blanket mortgage from a lender that offers them may be the solution you’re looking for. 

I think your easiest solution here is to find a way to satisfy their request.

So did you approach the bank with this solution? 

The best solution I think is to vet tenants well and find tenants that won’t destroy your house.