You'll need
2 Controllers

Stinger
Blind Eye
Hardline
Sentry Gun
Strafe Run
Assault Drone

1.You and 1 more person get in a lobby with your guests signed in, Search for a team tac
until it's SnD.
2.Invite the other 2 players with their guests signed in.
3.Pick One person from each team to go for that game. Everyone and Their Guests Spawn In.

Primary: Any (LMG recommended to shoot down a final heli from strafe if you fail your stinger or are using Javelin)
Secondary: Stinger (If you are <40 - either use a prestige token to unlock (must be Prestige 1), or just get someones Player 2 on other team to leave it out so when you kill them you take it)
Perk 1: Blind Eye
Perk 2: Hardline
Perk 3: Your Choice

Now, The Killstreaks:
Sentry Gun
Strafe Run
Assault Drone

Basically, the same setup as normal strafing.

Now, where the modification comes in - The Process:

So since we have a limit of 50k, we need to improvise. In this process, both players will get to kill.

1. Assign yourself a partner on the opposite team.
2. You go to the enemy spawn and kill the 3 AFK players (Everyone but your partner) - your partner does the same at your base.
3. After killing, meet up at a bomb site and let the planter plant while the defuser defuses.
THE CHANGE
4. When it reaches 3-0, switch players. Meaning that the 2 people who weren't killing are now killers and planters/defusers; rather than the same 2 going the whole way through.
5. Call in killstreaks as per normal. Destroy your partners killstreaks etc etc.

This way you should roughly get 40,000-45,000 exp; never pushing the 50k mark. It may seem vastly slower, but remember. You get this every match! (As opposed to every second the normal way)
That's basically it! CREDIT GO'S TO LEKIC FOR THIS METHOD

Also credits to Collin Boy as it is from his thread.