@roweda, et al,
re the weakness of the holes after filing them out.
I recently helped a 3 people get started with PaW and building them into the stratux cases, I left them to adapt the cases and the result of one was very large holes offering next to no support! while searching for an easy solution I found MilliPut, simply brilliant, it an epoxy putty.
Very easy to use and apply and sets rock hard. I filled the holes leaving only where the hole should be, it seems very strong. I was so impressed I also filled mine too and it seems to have done the job. You do need to allow it to dry/full harden overnight, but after that I could file it and sand it without issue!