Thought that I could speed things up now I see the finish line... made a large batch of epoxy (you can tell what's coming) with 410 so the filling of all the corners and unfair surfaces a could be done. I put all of it in a plastic bag so I could cut it's corner and push it out into the corners. All went well until the plastic bag and its content started feeling very hot in my hand... The filled epoxy all of a sudden went rubbery and it was very tough to work with. The contents were quickly spread to the corners to reduce the volume in the plastic bag as much as possible. Then this was cleaned up and made reasonably fair. It did fill all the big gaps well.
The lesson is to stick with small batches and be patient with the process. When this project is done I will miss working on it so there is no reason to rush.
I hope the epoxy will be OK after it sets.