Yeah, the ultra mute, stuffing the f holes with foam, stand bass on cushion, wrap a heavy towel around the bridge and stuff the ends between the tail piece and the bass will help a bit. You can also weave tea towels or t shirts around the strings at the bridge. Play into an open waredrobe that's full of clothes.
Hope that helps.
"....all those low frequencies vibrating through you, its gotta be good for you right?" - Captain Mission