I know I will aggro hate for this but, why not have a BG that it mixes both sides? Mix up guardians and defiants. Guardians might dislike this idea, and Defiants might like it. I have characters on both sides and i notice up to 30-40 on my server defiants lose like 85% of the matches, the wins mostly being premades. On a different WF cluster for gaurdians, we win 80% or so of the matches 10-30 (i havent gotten past 30 yet).

Pro's
Shorter queue times
more even (win/loss) matches
less side switching because "losses"
more people in WF's cause one side wont lose every match

Con's
doesn't really follow lore
some guardians wont win as much..