I don't know what airports you guys have been flying from , but the major airlines at the larger airports all have these newfangled sizing templates at the gate where all carry-on luggage must be X-Ray scanned. There is no way a guitar is going through one of these, either hard case or gig bag, so I don't see the virtue of trying to brass it out, as it ain't going to work.
I have changed my views completely on the question of carrying guitars on board. I have travelled internal USA and transatlantic many times, and "smuggled " my guitar on board each time, but I won't do it any more. If you invest in the best possible flight case, and pack rhe guitar well with bubble wrap, damage is very unlikely.
I cannot agree with the advice to brazen it out. It might work nine times out of ten, but one of these days you will be forced to check it in, and then, if you haven't taken adequate precautions, that is just when your guitar WILL get damaged. And besides, anyone who stores a hardshell case in the overhead is being bloody imconsiderate, IMHO. I always took mine on board in a gig bag.