Sasless,
Since we were in the Delta, we were supporting the ARVN 1st Division(I think) and did not cross the Cambodian border until 10-14 days after the others crossed near the Parrot's Beak. We launched basically north to the town of Tuc Meas, the first day being the roughest. Lots of antiaircraft fire, and shot up ARVN's, including some US Army advisers. We did not lose any crews until after we pulled out about two weeks later. Must have really stirred them up.
The U Minh forest was the worst place in the Delta, though not really a forest. It was mostly palm trees and low brush in a huge swamp. We had four aircraft shot down on the southern edge, but managed to get all of our guys out, some wounded and sent home. We did lose several ARVN, about 25 I think.