Via Defcon 17 how to file safer with your checked luggage
this is sort of doing a judo move on the regs but
use a hardcase suitcase and then pack one of your markers UNLOADED. have a nice sturdy lock on you NOT TSA APPROVED. when you get to the checkin very calmly state that you have an unloaded firearm in your luggage (and wish to declare same). At this point according to FEDERAL REGULATIONS your bag cannot be opened without you being present.
Oh and btw its FEDERAL LAW you must have a non-TSA approved lock on your luggage if it contains a "firearm".