I was talking to my dealer about this exact thing when these "one shot" trust deals came out from Silencer Shop. If that was the case, the dealer could essentially file them and then have them at the ready at a higher price for people who were willing to pay more not to wait. He said he wouldn't be doing it but we were simply discussing the legalities of it. I've never talked to a lawyer about it, but it should would be kind of nice really. One time stamp and essentially no wait for things down the road.
I just pinged the question to a buddy of mine who is a lawyer down in Florida. We'll see... I've learned that lawyers are the cagiest people when asked to give professional advice. Usually, when asking folks in other professions, you can't get them to shut up about it.