Real easy with 2 players boosting. Takes around 1 hour for both combined. I just did this with PriorKarma (big thanks) so credit also goes to him.
Game mode: Ranked team elimination
Map: any (canyon 810 has the suicide off the cliff option)
Battle guage: 2500
Weapons: rockets
Method:
Who ever is going to WIN do nothing, just sit there.
Your boosting partner waits for the blue shield to go then kills themselves with a grenade (not shock), a rocket or two or if near the cliff edge jump off.
Rinse and repeat 10 times then swap over
It is that simple!