I honestly don't understand the problem people have with showing a tax stamp. I'm relatively new to NFA stuff, and every time I've been to the range lately, people ask about my SBR and homemade cans.
Range officials sometimes ask if I have a stamp because they know that ATF is always looking for ways to shut them down. I also know this, and since the ranges I go to are private property, I feel that they have a right to know if I'm legit or not......and since I want to be welcomed back to the ranges I go to, I don't mind showing a piece of paper that I keep in the pistol grip compartment anyway.
Fudds who accuse me of having illegal gear get a friendly conversation about how easy it is to file a Form 1. I take the opportunity to educate them about NFA and clear up some of their misconceptions. I don't know if I've 'converted' anyone, but I've found that by being reasonable and friendly, I generally don't have any problems with them later. The one time I did, the range official lectured the Fudd about 2A rights and kicked him off the range for being an asshole.