You wouldn't want to increase your rear sprocket size if you can help it, I can think of a few reasons:
Ground clearance comes at a premium on Banshee's especially for trail riding, increasing the diameter of the rear sprocket will reduce the ground clearance. If anything, try to reduce the diameter of the rear sprocket for trail riding.
Rear sprockets are way more expensive than fronts so why go that route?
It's easier for me to change the front sprocket than changing the rear.
Like the others said, get a few $7 front sprockets and experiment. See how you like it, if you don't, then no big financial loss...