I have not been able to convince the nonprofits on whose boards I sit to adopt a mileage program but I have been a consistent donor to the NPF, which awards 10 miles per dollar. Here's the details:

https://www.donate.nationalparks.org/Donate/Donate.asp
https://www.donate.nationalparks.org...rtner_aa.shtml

10 miles per dollar is a typical reward for nonprofit contributions, although I can understand if board members find it a little "rich."

If your board adopts the program, I hope you will alert me (by email or PM) so that I might contribute.