Another way to boost, I've gotten around 8,000 to 9,000 XP per game. You'll need a number of people for this, as I noticed a LOT of randoms logging on to grief attempts at boosting and they seem to really appear in this game type.
Check into an Icarus game with friends, the more the merrier. The best maps are pretty much anyone EXCEPT Fort Knox.
Gather everyone around Console #2. There is a line, a buffer around the console. You need to find that line and stand on it and that way you'll collect 200 xp every time the console is captured by either side. The best way to find the line is when the opposing team is capturing the console, walk up to it so the CAPTURING stops, then slowly inch away from the console until that warning disappears. Basically sit here the whole match - keep flicking up your iron sights / scope / red dot sight / etc - to prevent from being booted for inactivity. You won't even have to move from the spot provided no one else does either.