However, there are many ways to calculate return and some formulas do not include all recurring costs while others include principal reduction and other such unrealized gains.

Wait 12 months with (presumably) zero claims and ask for a reduction or shop around again.

You have to show demand for the space and only give short term concessions (if any).If a reduction is given you could try the base rent plus percentage rent so when sales go up you get income as the tenant gets healthier again.Once the lease is signed with a tenant it is like pulling teeth to change anything so be methodical and tactical in negotiations before executing a lease.

My gut wants me to get a bid for a new system and ask for reduction in the price.

I do notice lately a lot of price reductions, but that was just looking for a sfh for me and my family and possibly rent out the th I live in now.

But, I have no problem at all making money elsewhere... and I'm trying to model how to make that happen.To make sense of everything I know and think I know, I came up with the following model to roughly project returns at various rental rates and price points, showing expected Year1 returns based on leveraged free cash flow + principal reduction.  

You also mentioned doing a face reduction after the first 5 years.

If no, when you factor in principal reduction, are you doing better than monthy rent? 

If you mean the usage reduction, that's for whomever pays that bill.

The whole point of the LLC is the reduction of liability and protecting your other assets including yourself.