Hmm, you could maybe design it so the baffle plate lifts out and a basket/grill for the charcoal when your grilling goes in in place of the baffle plate... You may want some height adjustment, could end up being easier to adjust the height of the grill rather than the height of the coals...
The one thing I learned modifying my offset into a RF (you probably know this already) just make sure its properly sealed. Use fibreglass stove seal tape on both the door and the body and if it doesn't seal tight use cam lock latches to pull the door shut, it makes such a difference to the draw running through the smoker to have the doors sealed properly.