It would be an interesting idea, but I don't think BEL has enough land to run a scenario. CDWC has something like 70 acres. If you consider fort to fort as one mission area, there at least 8 of those at CDWC, plenty of ground for players to cover and run side missions without the place being over-crowded. Paintball Charleston is also very similar in size.
Imagine being swamped by 300+ players, if all the advertising worked? Yeah, nice to see those kind of numbers, but would BEL be able to handle them? It would take a serious amount of planning and work and the number of staff would have to triple as a minimum.
Without even considering the scenario/missions, things to think about for 300+ players:-
Air Fill Stations (Minimum 2-3 separate speed fill stations)
Chronograph area (Minimum 4-6 stations simultaneously).
Trailer load of Brand New paint (At least 2 boxes per player) thats 600 boxes min.
Restrooms (At least 4 - Portables).
Parking lot - Needs to be able to cope with at least 200+ cars?
Food/Drink for 300 players?
D.