Our biggest mistake was "respecting Laos' neutrality." Simply put, proclamations aside, Laos was NOT neutral. They were a de facto Vichy state in the face of Communist aggression. Sorry, but like France in 1944, we ought to have invaded their Vichy space, and occupied it with extreme prejudice. Overall, we ought to have occupied and utterly deCommunized everything from the Gulf of Tonkin to the Bay of Bengal, thereby inserting a zone of freedom in between Thailand and the PRC. And from that platform, onward with the roll back ... go North young man!
All you state could have been accomplished. Unfortunately, the political will had been systematically drained away by the comsymps of that era.