Preheat the oven to 375 degrees.
Bring a large pot of water to a boil. Cut an “x” into the bottom of each peach, then place the peaches in the boiling water for a minute. Carefully remove the peaches one at a time with a big spoon, placing them in a large bowl of ice water. Pull the skin off each peach. (It will come off easily if the peaches are ripe.)
Slice the peaches into 1/4 inch thick sections, and place them in a large bowl. Add the remaining filling ingredients (gluten-free flour, salt, and maple syrup). Stir to coat.
Place the filling in a 9 by 9 inch pan and bake for 20 minutes.
Meanwhile, prepare the crisp topping by mixing together the oats, cornmeal, walnuts, coconut, maple syrup, cinnamon, salt, and coconut oil in the large bowl that you used for the filling ingredients.
After the filling has been in the oven for 20 minutes, remove the pan from the oven. Cover the fruit evenly with the crisp topping and return the pan to the oven. Bake for another 15 minutes, or until the topping begins to brown.
Cool on a wire rack. Serve warm, or chill in the refrigerator for later.