I think you'll be able to drum up a good deal of interest for this.
mb-airsoft.com for the MAA and
http://www.operationcoldfront.com/ for MOUT/ Wolfpack
You can also talk to people on both sites about the logistics of running large/ regular games if you don't already have that experience.
It will be great to have another field to play at, especially if the theme/ dress code is enforced (at least for a few games in the season).
It may take a while before enough players have plausible Vietnam kit put together en masse, but I know of a few different people who have been hemming and hawing about doing it, and this may put them over the edge towards finally getting some loadouts done.
I for one will gladly wear sandals in the bush and scream all the threats and obscenities I learned from Battlefield: Vietnam.