Maybe you could take one of those low profile TSA approved steel cases and weld or bolt it to the top of your swingarm crossmember, that is located directly under the rear of the airbox. I have one for flying, powder coated exterior, double locks with a single barrel key and a O-ring seal. Sorry, I can/t check clearances for you as I run DNA Pods and the airboxes are long gone. My TSA box will fit a 1911 or a Sig P220 with ammo and it's fairly thin, for what it is. It cost me $26 and change at Cabelas, IIRC.