fiberglassing, from what I understand, involves dipping a cloth into a resin and then putting on your project. Repeat until desired thickness/coverage is reached. Let dry, sand down and detail as needed.
That's the very undetailed overview, heh.
Bondo is typically a mixture of two chemicals that then harden. I haven't done too much with it, but yes I noticed it dries pretty fast and it does become very strong, which is why it's used to patch holes in cars. Someone told me that I may have had too much of the setter in my mix though if it dried as quickly as it did for me. But...yeah, bondo or fiberglass would work well to strengthen your project.
Looks great though!