When I was glassing on my new bonnet scoop I asked around all the local places and all they could suggest was to use any polyester filler as a bonding agent and considering I was glassing over both sides I went with that idea. I did end up using a fibreglass impregnated filler, but how that would go for bonding on an entire front clip I couldn't say.
Sounds like something worht investigating a little further tho. I'll try to find out for you if i can.