I have 6 tenants, though one is on financial assistance with a charity (not S8). 

The GC isn't running a charity and neither should you be.So if you told them or had a contract with them to do it at cost (without any stipulation as to what cost truly is) you would probably be able to argue that you should get the actual true expenses plus some admin fees and your time on the job without profit. 

I am currently involved in a charity out here in Denver that helps those in financial crisis.  

I wouldn't have done much worse if I gave them to a charity.

I really think the " QUESTION" is do you raise rents... if you do you keep up with inflation, if you don't your a charity,, Does the gas station at the corner care if you drive a beater or a new car??

Landlords planned for a rainy day, but they didn't plan for the federal government to come in and tell them that their business is now a charity whether they like it or not.

He is not a charity! 

You're in a business world, not a charity 

- How can I maximize the good (Do I give money to a charity?

First you are correct this is a business not a charity or non profit or community service, save community and charity work for the part of you life that you have dedicated to those causes, which by the way is a must if you want to be a complete self actualize person.