customer body kit

so i have a very cool little project going on a old school car with a new look. basically im doing a customer body kit. i took the bumper off one of one car and choped it down to fit and fiberglassed it up. its nice and solid in the fiberglass part. but i messed up on the sides a little bit and im going to have to use slightly more bondo than i wanted.... my concern is cracking. this needs to be show quality, i dont want to spend 6g on a paint job just to have my bondo crack because i had to use to much. really im not using that much but im just nervous i guess lol. anyway my question is.... after i get the bondo on, and sanded down, do you think if i laided a layer of fiberglass resin over all of it and sanded it down some, it would keep it strong and smooth and round, and maybe prevent from crackin? ive never heard of anyone doing it, but i just thought about it and in my head i think it would work great, but what do you guys think? good idea? bad idea? worth a try? any info? im not a noob when it comes to this kind of work, but im not pro. let me know what you guys think, thanks.

How thick is the bondo? If it is more than 1/8" thick I would just grind that away and fill in with duraglass. Then skim in bondo for smoothness.

I say give it a try, but if you are looking for show quality on a car that will potentially see a lot of driving time and the bondo needs more than 1/16", then I would just redo it in duraglass and use bondo as a skim coat for smoothness.

Ganbatte ne!