Here's another idea - call me crazy, but....
How about just locking the gun up in your vehicle (you do carry a lockable case at all times, don't you?) and just going into the show gun-naked?
You only have to traverse a few hundred feet un-armed, but will soon be safely in a crowd of fellow gun folk. You don't have to wait extra time to check your gun, don't have to fool with the tie-wrap, and don't need to worry about collecting up everything afterwards.
Granted, if you are bringing it in to check the fit of a holster, or looking to sell the gun, that's another matter.
But to avoid the hassle of the customary "gun frisk" walking through the door, just leave it in the car. There are guards in the parking lot, and no one is going to fool with it.
If I was going into a gun show in downtown Boston (HA! What a thought!) it would be different. But in Marlboro? In the daylight? Surrounded by gun folk? I'll take a chance and drop my alert level to orange temporarily....