No Vehicle is invincible, the lowly Plasma Pistol is the ultimate BANE of all vehicles and every BTBH I have played has had a Plasma Pistol on it, if you are clever enough and can get close enough without being seen you can take out ANY vehicle , including the Wraith, the Scorpion, hell even the flying Falcons and Banshee., with nothing but the Plasma Pistol and a single grenade.
If you are supposedly so skilled and they supposedly suck so bad then you should be able to reap havoc with these kinda tactics.
If I can do this and I am not that good at all (look at my BPR), and I can do this a lot of the time. Imagine what an expert like yourself could do.
Also most BTBH maps have the grenade launcher, which does the same thing as the plasma pistol and can get to places the plasma pistol can't, the map makers gave you options to counter the "noobs" who spam the Scorpion, just use the tools they gave you.
If you get desperate you could even use Armor Lock, though I would understand pride not letting you do that one.
[Edited on 03.21.2012 7:28 PM PDT]