Yep.... I have a paging alarm system on my vehicle that calls my cell phone for just such a reason. I have a custom welded in recessed locking floor box that fits flush with the floor board and hides under the floor mats for my toys that I leave in the vehicle. It will hold a MP5 full up or M4 carbine with the pins pulled and taken down .
Works well to not leave goodies in view....dark limo tint on all but the front drivers and passenger windows where "legal tint" must be used also helps.
Flush with the floor eh? That's cool! I'll tell them about that sort of box. She "thinks" somebody tipped off the thieves and then waited until they were out to supper in another vehicle because it was pretty much out of sight, and really didn't look like a gun box. But I'll tell him about the sort of box you're using. Thanks! :-)