Lorann Banana Cream may be what you're after here. You can turn the TFA BC up to maybe 7-8% but it gets pretty gnarly past that. Try turning the graham crust down to 1.5% because it doesn't steep out and stays pretty damn strong in a mix. Vanilla swirl may actually me hurting the mix too, not guaranteeing that it is but it's possible.
Try making a tester of;
6% TFA Banana Cream
1.5% Cheesecake graham crust
Also throw at least a 10ml of Lorann Banana Cream (colorless) onto your next order and try it at 6% with 2% graham crust and 2% Vanilla swirl.
Edit: Cap Sugar Cookie at 3-5% will give a nice vanilla wafer note to the mix.
Edit 2: Flavorah Banana reportedly tastes spot on to store bought banana pudding so that may be even better suited for your needs.