No, don't do that.
When you get your bondo body filler, make a dog poop sized pile of it on a piece of cardboard(make sure its large) then add just a bit of hardener cream(it comes with it) then mix using a wooden paint stick. use the same stick to put it on. you can do alot with a little bit, Hell my helmet is almost covered and I still got most of the can left. after it hardens, sand it down with a Cheese grater(go to the hardware store, look in the carpentry tools, near the wood files) its also called a surform plane, just ask about it. sand it down. Take a dremal and work out the details.