Macgyver.......
I'm going to be a bit of a wet blanket here
Sorry, a few guys are "inferring" issues with the glass and bondo, but not coming out with real information for you.
Here is my take on this after 30 years experience with glass and bondo.
The 1st photo shows you draping a piece of cloth over a couple of hoops.
Fiberglass cloth with resin has no......NO strength , NONE it is as fragile as a thin piece of glass. Some sort of support would be needed to have any strength. The bondo you have put on, while it seems to make it feel stronger gives it NO Support. There are many different things you can add to bondo to make it a bit stronger, but in the end it is designed for a VERY shallow film over boo-boos left over from other heavier fillers on the market that have been layed on a few times and sanded.
The 1st Bondo photo you show "below" kicked 10 Min's before you even layed it up. It's hooped. Sorry, but you can not lay up glass resin or any 2 part system after it has all ready gone off!!!! Bad start, and when I see it happen I scrape the last bit and worry about sanding it down later.
I truly wish I had seen this post before. I would have tried to help a bit more along the way.
Please do not spend any more time making these pieces perfect for your build.
Bolt them on as is and ride it for a while. See what happens.
If that rear seat piece does not crack, split, or explode after being bolted to the frame for 364 days I will personally mail you a check for $100.00. I will require a photo of your OD before and after so I can see it was ridden
Not trying to be a dick head here Laminar, ..............come on guys ...........tell him what you realy think