The Republican Party was once a third party, no?
The rate things are going, it will be one again.
How would you caucus in an legislature?
How would you control any legislative body, local, State or Federal?
How would you avoid hurting conservative Republicans and THROWING elections to Liberal Democrats?
Your complaints are, for the most part, complaints against human nature.
those SAME complaints will crop up, RIGHT AWAY, with any other Party, no matter what the name, no matter who you attract that you like. There WILL be traitors and crazy people and cowards and idiots in EVERY political party.