Looks really great, but my concern is the fact that it only builds a pentagon shape, limits it for a gaming perspective:
If the whole table is the firebase, then the action takes place on the interior, rendering an outer perimeter a bit redundant.
I think an improvement would be the ability to have a few different angle joints, to represent an attack against a single corner, or to make the firebase a more interesting shape.
Also selling the Vietnam war is always tricky, I don't think its the most popular for gamers.