I never had any real problem with this map, but I'm a little odd sometimes.
I clear the hobo camp & tent with a close combat scout/medic and my GL w/rocket launcher. Once that alien is dead the CC plays medic and the GL switches to the rockets and stays high to scan the inaccessable plateau. The CC also carries extra RL missiles, he drops some of those up there.
Run a GL to the base of the hills on the right, below the small cliff and out of LoS. Have a laser or MG covering the hills from the trucks. When the shooter spots an alien the GL arcs 'nades onto him. If you have aliens hiding in the alcove along the road rain some GL-loving on them. After that move up to the top of the hills, GL spots for the shooter. Clear the top and move to drop more explosives on the end of the convoy.
My last four guys camp the trucks. I've done the map with RF and active fire, it works both ways. Two snipers and two heavy lasers or any similar combo works. Stay at your end, always have someone with a medkit behind the truck, heal anyone not at full health, stay crouched and keep the aliens at the opposite end of the map. Your accuracy over long ranges will keep them down at their end and you have that GL working up over the hills towards them.
Part of the reason I get away with having so many snipers and long range weapons is that I carry a flamer in the backpack. It's accuracy and damage at close ranges mean that dedicated snipers with no other skills can function in a close combat environment. Also every slot on a GL's belt should have reloads, the holster gets a pistol and reloads, the backpack gets a medkit or rocket launcher and more reloads. Pack as much ammo as you can onto your grenade launcher guys, this gets more important in 2.3 than in 2.2, just don't be stingy with ammo.