OK, Boys & Girls, I made the 30 Amp external Power Cord mod this past weekend.
I purchased the 3 parts at Camping World for around $115
Used the Gasket to layout the cutting circle with a fine point marker. Then, drilled 1/8 inch holes around inside of circle. Then cut around circle with small fine tooth Sabre saw blade held in Vise Grips.
Drilling and cutting done
Taking piece out
Then I used a Half-Round file to fine tune hole for mounting hub. and then did a test fit
Test fit of mounting hub
30 Amp power cord and attached to exterior receptacle with gasket and hub on cord. Used 1 1/2 inch Stainless steel machine screws with washers and Nylon lock nuts on the inside.
Installation finished. Lot's of fun getting Rat-fur and insulation out of the way so I could install and tighten Nylon lock nuts down.
Mounted Plug on end of 30 Amp power cord and this shows it attached with the weatherproof cover screwed up in place. This also holds the cord in place.
Again, please feel free to contact me if you have any questions or comments.