For the graham crackers: Preheat the oven to 350 degrees F. Whisk together the flours, baking soda, cinnamon and sea salt in a bowl. Beat together the margarine, sugar, molasses on medium speed in a mixer until light and fluffy (scrape down sides). Add the flour mixture and mix until well incorporated.
Roll out 1/8-inch thick on a baking sheet and use a cutting wheel to cut into rectangles and prick with fork. Transfer each cracker to an ungreased baking sheet using a spatula, spacing them about 1 inch apart. Bake until golden brown, 15 to 18 minutes, rotating halfway through. Cool completely (crackers will be crisp). Halve 12 of the graham crackers and reserve for the s'mores. Set aside the remaining graham crackers for another use.
For the s'mores: Thread a marshmallows onto a skewer and toast over a flame until melted. Sandwich 1/2 ounce chocolate, one slice banana, and a melted marshmallow between two graham crackers. Repeat to make 12 s'mores.