I had high hopes for the Soudal Fix All, but under test, it easily pulled apart and could easily be peeled of the plastic.
See video: https://youtu.be/VfRNuWb2qQc?t=288b
Yeah, watched the video before I posted, with the large surface area it doesn't have to grip that well. Maybe bathroom sealant would do in that case.
Have a read up on 3M adhesives, they are stating good peel resistance and shear strength. They do an epoxy as well as the acrylic I mentioned.
It's only the motor and servo mounts that need to be securely fixed though Ive even got my servo/ESC mount secured with Velcro, though it is plywood, and has survived a few battles! Oh, and the rudder mounting, which is the important one!
Chris