Maybe have staff members who are respected members of both parties?
Or set up individual wealthy donors who are planning to donate roughly the same amount with one another and have them place money in escrow?
If we find such wealthy donors, we could match them against each other instead! But I suppose it’s possible that we’d find donors who’d be willing to match with each other up to however much is contributed to the platform, as a way of raising interest. Like how cool would it be if Sheldon Adelson and George Soros agreed to this sort of thing? (I’m not even remotely optimistic though :P)