I love the .22/20ga camper special. Get a butt stock elastic 5 or 6 shell carrier with a flap. Sew a bunch of .22 loops on the inside of the flap for extra ammo. You can carry 1 or 2 12 ga "survival kits" and fill the remainder of the carrier with 20 ga shells, plus 10 & 2 in the butt.
I'm thinking of having my .22/.410 Savage 24 cut down to 18" barrels. A deluxe M6. A rifle caliber elastic shell carrier fits .410 shells very nicely!