Well, if by some odd chance the ATF would check you then you have to provide proof of registration (a copy of your stamp does that.) If your suppressor is owned by a trust, a copy of the trust should accompany your stamp so that you can show that you are a trustee and then a valid state ID could be shown for identification. With regard to Texas authorities I believe it's a "otherwise legal" situation so I would follow the same policy as for the ATF. Of course, you'll get other opinions................... An attorney that handles NFA items in Texas would be your most sound resource.