I think a third part is just going to muddy the water. What will happen is that they will either be a player or not. If they aren't...they will not matter. If they are; they will spend half the time fund raising to get re-elected too and thus be subject to lobbyists, special interests, etc...A third party may be exactly what is needed.
You're exactly right about this.As long it is not at the extremes of either party, it could serve as a legislative dam buster. The polarization in politics makes it almost possible to pass significant legislation without full control of government. Since that happens less half the time, we are sending congressmen to Washington half the time to accomplish little or nothing accept to block the opposition party.
We don't do big things any more. We do a lot of little things. Can you imagine suggesting the TVA in this day and age? NASA would never happen. And it's directly attributable to just what you said....you have the party of "no". Our global competitors don't suffer from that malady and it's beginning to show.
I heard, a few times, about a fulcrum confederation of members of both major political parties. They would act as a counter balance to the radicals. But that seemed to be a pipe dream.
I saw a movie once called The Star Chamber. What would happen is that judges who are hemmed in by the law and precedent and had to let people go on technicalities who they knew were guilty would hire hit men to take out the criminals that they had to legally let go. The judges had a panel that would vote on whether or not to serve the death warrants. I wonder if something like that where they would meet in private and discuss privately (in a binding way) on how they would vote on the floor.