This is a business not a charity .

Maybe donate all the earnings to a charity, but then you would not be paying taxes because you have no earnings.Only sure way to not pay any taxes is to give up US citizenship, but that is perhaps beneficial only for older retired people.

But remember, you're not running a charity and it's not your fault that the item they wish to purchase has gone up in price. 

If you want to run a charity, charge people market rate and then donate $30,000 to a charity that helps people that are really in need.When people are that far below market rate, I don't even give them the choice of staying at the higher rate.

Our goal would be to source projects and attach them to local or global causes (like a BRRR SF home with monthly cashflow supporting a charity drilling clean water wells in Africa, etc).

Have compassion, but also remember you're running a business, not a charity. 

Zelle, ACH are great free ways for some tenants to pay rent.  

For all I know you may in fact be running a charity. 

You're right this is a business, we didn't start this to be a charity.

You don't have to be cruel about it but you do need to decide if you're running a business or a charity that subsidizes living expenses of strangers.