Be aware that those 'switch boxes' can be built with about $10-$15 in parts. They consist of a pair of BNC bulkhead females and a 1/8" 'normally closed' jack, like what you'd find in a 'boom box' with an external speaker jack. While they will work fine, they will almost always destroy your carefully set up SWR (if you sweat that).
The simplest, lowest loss, cheapest, and most reliable method is just a bulkhead mount BNC female on the end of the a/c antenna cable, and a male/male cable from the panel mount radio. Mount the BNC female where it's in reach (near the bottom edge of the panel usually works), and if the panel mount fails, unhook the coax from the panel mount and attach the coax from your handheld.
Did I mention that all this stuff has been covered ad nauseam on the Aeroelectric list, and I'm pretty sure it's in 'the book'. You do have the book, right?
Your issues with Icom is an example of why I'm not much of a fan of their stuff. ('It's not a bug; it's a feature....')
Charlie