I don't feel like you need to go through the same hurdles you went through with Sarah's Jenner. Maybe in the interests of transparency, you just set up a page that shows the stats (sales per day) and does a quick tally showing how much is being sent off to the charity in question. Just pick an MC exchange rate (ideally a favorable one) and translate that into currency for the donation.
Yes, if you are the one donating, then it's not a tax-deductible donation for us but one your company can enjoy. I don't care honestly as long as the money gets to the right people (which the charity can also verify).
To make it more fair or cultivate more community interest, you could put the mech and general loadouts to vote (i.e. give us three possible mechs, then give us three possible loadouts, etc.).
In the end, I think we've got at least a core community that should and would love this. Some of us complain without end but I figure they're the ones that care the most about the game.

lg