One fabulously rich person (or a gaggle of them) would put X million dollars into a trust that expires November 9th. X would have to be very large. Probably several hundred million.
The rules would be simple. You could choose a funding cap for all candidates, x, which is much, much smaller than X. Say, $100 million. Plenty of money for a modest number of attack ads, since the parties must have a little fun.
The key: If any one candidate’s super PACs raised more than x, then the trust would automatically release an equivalent amount of funds to the opponent’s super PACs. The trust would be ready to hurl all its money if it must.