It has been done before, with several different charities, from obscure ones to national big name ones.
I set my charity up with Make-A-Wish FOundation, basically people would contribute as I hiked, passed out flyers to coworkers, friends, etc. It is one of the many reasons I was unhappy to leave the trail after thrashing my knee after only a few weeks…
Approach the charity of your liking, explain your idea (many require you to fill out a set of forms laying out your plans) and go from there… If they refuse, find another. You can even set one up yourself and donate it afterwards, using a bank account set up for that specific reason, your bank officer can explain how that works as well.
-xtn
airferret