Depends how good a shot you are, mind you some days I'd swap my shoulder for a PCP as a break barrel can't be doing it any favours.

Well if extra cooling is needed/wanted just shout, in my pack will be my Yugolsavian mess kit that holds about 750ml to 1l and the shotgun flask that I'll do either Cappucino or tea in to drink either there or on the road and probably a 2l of Fizz as booze and meds aren't too friendly.
Can bung basic tools in there too if theres a need for emergancy repairs but can't go too mad as won't be able carry it.