You really don't want an exceptionally light 12 guage. They hurt to shoot. A shotgun with a pistol grip only is the most useless thing on the planet. A folding stock isn't much good either due to the time it takes to open. You'll never be fast enough to deal with, say Yogi, anyway.
I suspect issue with the pistol gripped stock may be the stock length vs the pistol grip itself. Start by checking that and fixing it as required, then look at other aftermarket stuff. As I recall, Mavericks are the same as Mossberg M500's so finding aftermarket stuff isn't a nightmare.
