Bags can be reused a limited number of times. A tiny leak totally ruins results so be conservative.
A partial cooking and then once the baked good is set, finishing it propped up toasting in the fire heat can give a nice crust. Same principle can turn out pizza-ish dishes, cook the crust and set the toppings in a pan, then toast the top at as steep as angle as you dare in front of a fire, frequent turning.
I still recommend perfecting Bannock, it can be superb and the same basic mix can turn out as a herby savoury extra butter crust over little trout, breakfast biscuits or as a sweet shortbread full of red huckleberries in a blueberry sauce. No oven required, a stick (with a few prongs for grip, some engineering needed, the bannock slowly sliding off into the fire is a teachable moment all kids should experience before they're 8), a fire and some time turning it slowly.