I've never owned a Bushnell 3200. But having owned a truck load of handcannons over the years, I think its a fairly common problem depending on the chosen scope and rings. Scopes with belled lenses and not a lot of tube diameter space on either side of the turrets can be a problem to get 3 or 4 rings on, and give you very little latitude on the scopes position front to back. With some it just can't be done without modifications. If you want to stay with your scope and ring choice, and it does have ample room for 2 rings between the turrets and end bell(s), probably the easiest would be to get a machinists to cut a new slot in the base. Been there, done that.
I ran into a totally unexpected problem with 4 top end SSK JDJ handcannon barrels I bought with the full length T'SOB vent ribs and T'SOB rings. They gave me fits with any scope with belled objective lenses. Had plenty of space for 3 or 4 rings while using the provided base slots, but the scopes objective bells would not clear the vent rib with either style of T'SOB rings. So my problem was ring height, not spacing. Came down to either using higher rings by another maker instead of the T'SOB rings, or scopes with a non belled objective lens. Considered that an oversight on both styles of T'SOB rings by JD - not offering higher rings for use on their vent rib barrels with belled objective scopes.