Never understood the idea of "woodsball" equipment. Mostly, in the way of guns, it seems mostly to be outdated technology dressed up to look like military kit and thus ending up heavy and unweildy!
As such, any hopper could be used in the woods, though you may not choose white or red shells! On a budget, a Halo or Reloader B for £25-40 secondhand is theway to go, if you have a little money, a Rotor is a fantastic loader, and available in some camo'ish finishes.
Halo uses eyes to sense the paint moving, where as the reloaders series uses sound activation to hear the gun fire and feed. The B is adjustable for speed, whereas the B2 allows you adjust the speed, sound sensitivity and the turn the stack tension monitoring on/off.
Personally I own a pair of reloader B2s, and have used the B and a stock Halo. All excellent hopper, but the Reloaders are slightly more user friendly in that they never fail to feed (the Halo has issues with some paint colours) and the LEDs make it clearer when they are on or off. The B2 edges it over the B as the B needs to be switched on somewhere quiet to allow the sound sensitivity to set itself - if you switch it on somewhere noisy it can fail to feed.