My primary expense is mortgage taxes and insurance, Since that is added to my numerator (debt) wouldn’t it be foolish for it to subtract from my denominator (rental income) as well?

The calculation of subtracting MV with what I currently owe equals that.If this was the amount you had, what would you do with it?

@Tim Herman after subtracting mortgage, 10k for repairs/maintenance, property tax, property insurance, licenses, and everything else you can imagine, I have a cap rate of 14%. 

Subtract $75k and you're at $431k.

If you subtract contractors overhead and profit of 25% and the allowance that leaves about $20k for cost of the work.Did you get any other quotes?

The only exception I can think off offhand (and I'm sure there are other examples) would be a landlord doesn't fix something that should be fixed (non-working furnace), the tenant pays to have the repair done, subtracts the repair amount from the rent check and the landlord demands full rent claiming he didn't OK the repair or repair cost. 

My only caveat- I subtract 30-35% of total income to the "invisible" expenses of vacancy, maintenance, capex, and property management.

Then subtract property tax, maintenance, etc. and it’s way less than that.  

Calculate the NOI by multiplying the number of occupied spaces by the lot rent, and then multiply by 12 months, subtract the expenses (can range from 30-50%, that % depending on the variables above).

You should be able to determine rents for the different types of properties and subtract operating expenses to get to an NOI.You can talk to local commercial brokers for some guidance on potential uses and income and expense expectations and assumptions.