Taken from Robin Hood flour website:

1 tsp (5 mL) sugar
1/2 cup (125 mL) water, warm
1 envelope (8 g) active dry yeast (2 1/4 tsp/11 mL)
1 cup (250 mL) milk
2 tbsp (30 mL) butter or margarine
2 tbsp (30 mL) sugar
1 1/2 tsp (7 mL) salt
1/2 cup (125 mL) water, warm
5 1/2 cups (1375 mL) ROBIN HOOD® Best For Bread Homestyle White Flour

Note: this makes two loaves of bread.

For your purposes substitute shortening for the butter, mix all the ingrediants together (except for water) before leaving home. Bring along a seperate bag of just flour for the kneading portion. Also bring a little oil or shortening to grease your pan for both the rising of the dough and for when you bake it.

You don't say how much experience you have with baking bread at home. If you have none, then bake lots of bread at home before you try to master it on the trail.