The Fair Representation Act has been sponsored by a Democrat every time.
It's orders of magnitude more probable to get the slim minority you're talking about to align D than it is to get the overwhelming majority I'm talking about to rally behind the same third party candidate. It's not even worth comparing, the concept is laughable at best. To even hint at that happening this election is bordering on clinical levels of delusion.
If you want to campaign for your candidate next cycle, be my guest. Start early, organize, fundraise and get the message out. Next cycle. This cycle, you're dividing the anti-Project-2025 voting bloc. This cycle, you run the very real risk of ensuring there is no next cycle. Remember that.