Eminem is the best freestyle rapper in the world. This young kid is the best freestyle fiberglass fender sculptor in the world. You can make millions kid just being a natural!
The filler is not supposed to be structural, you really dont want it more than 1/8th in thick. Your repair would be more legit with more fiberglass cloth. Build it up, sand it down, then skim coat the whole thing with filler as thin as possible. But cool deal anyways
As a 'glass man' there is no way I would do what you did but, I'll give you a tip that'll help you next time. Wet out your mat on a sheet of waxed paper, it'll give it backing and it will hold its shape better. You can work into the repair, see where it's laying in, and you won't even get your hands messy.