I want to recoup my costs and donate the profits to a charity.

Managing it isn’t as easy as some of these youtubers and RE gurus make it sound likeIf you want to help people with sad eyes volunteer at a charity

It's a business not a charity.

Keep in mind I live in the same house so I don't want to create a hostile environment but at the same time it's a business not a charity. 

You're running a business, not a charity.

Unless your running a charity event type business then more power to you!

Learn about imputed interest which is minimum interest  Learn about reverse mortgages compared with installment sales , A good source is AARP  Learn about annuities and compare them with installment sales  Use the term legacy, leaving a legacy of your children or church or a charity "The cash flow survives your death  Mr. seller meaning that your gift can be inherited by someone that you care about or some institution you care about" If the seller is gainfully employed with W-2 income, and it's a free and clear house, you can have them get a 50% mortgage, then buy the house subject to existing financing, take over the payments, and give them a single payment note for their equity There are between 34 to 40% of all houses that are free and  clear of mortgages.

Instead you are running a charity without any of the benefits of running a charity.

Once you establish the CRT that remainder which would normally have belonged to you and your heirs now belongs to a charity.  

It is not unusual for a charity to ask for a W-9 when making someone else's rent payment.