Use a hole saw and cut one round hole. Then cut three disc of plastic, one being same diametter as hole you just cut, and two some bigger. Assemble the three and drill a single screw hole and assemble them stacked. Then drill two / three / or 4 holes as needed so all pass through the three disc but miss the screw in center holding them together. Now dissasemble the three and notch each hole to an edge .... but different for each hole in center smaller disc versus larger outer disc.
Mark "top" for each.
Place radio, run wires, bring through hole in saddle bag, have couplings on each so they can be disconected (as there will be times when this saddlebag must be removed for service) and then simply assemble the three disc around the cables / wires with a parge disc inside bag, a large one outside, and the smaller disc sandwiched between them filling the hole.
The slots you cut in different directions will allow you to slip cables into place in each disc and the slots should overlap going in different routes to edges. Screw with nylock nut will keep disc together. Silicone won't hurt to seal and is easily pealed off and redone in future service.
Just a suggestion. :waving: