BASE vs skydive wingsuit opening technique
Just create a good, small body position as/after you throw out your PC, so there is minimal burble. Make sure the body position is symmetrical, and no dropped shoulder, knees or de-arch present.
I usually fly (normal up to ballistic speeds) after separation, than initiate a slight flare by raising the head/chest (to slow down). Then grab PC, throw it like a man, then go to a small/collapsed body position. Skydiving I tend to go for a small collapsed body position vs 'keep flying the suit' during base deployments. And never really have issues switching between one or the other technique, depending on the environment I'm in.
Though a base style full flight opening technique also works, the collapsed body position taught during 1st flights is less prone to punish slight asymmetry and other 'cosmetic' mistakes in angle/body position.
Do make sure that during the initial swing, you don't open the legwing, or present any asymmetry (while you're still carrying a lot of forward momentum).
A 120 / 7 cell shouldn't pose to big an issue for wingsuit flying (I fly 2 rigs, one with a 120, one with a 135) and especially with a small suit, you should be more than fine.
Bridle should be a good long one (7 to 9 ft) but longer tends to just cause extra issues with the thing flopping around in your burble (when combined with a girly throw).
Stowless bag definitely helps in having clean/on heading openings.
