The tenant is currently paying less than current market rate, and we are only asking for an increase of 6%.  

If they do not pay their portion (if they have one) you say, " hey you are breaking the rules of your program, if you do not pay you will " lose your free ride ". watch how fast they pay.

There are brokerages out there that allow you to pay by transaction not by commission. 

You could refer the person to the state attorneys office because they knowingly had no intention of paying rent (or security) in that case.You may want to stay away from credit card payments since there can be a dispute by the renter for up to 6 months. 

If you make this a balloon payment in say 5 years, you've helped your cashflow, and you can refinance to pay out the balance of the 2nd mtg.I do have to ask though - you seem quite emotionally invested at this point - what are average house prices in this neighbourhood?

Plus I have tenants who are willing and able to pay market rent in the future.

I agree with paying attention to the DB but sometimes you will have limited options.

Looking at all the options on Zillow Rentals it seems like there's a lot of places falling apart and landlords want their tenants to pay for everything (no washer/dryer included, lawn care not included, first $100 of any maintenance requests, etc).   

These days what you would pay a plumber isn't that much different than you would pay a project manager.

Sometimes we pay to get the news.