My trust from a lawyer (Douglas Turner, in Genessee) came with a couple of pages set up just for bank accounts or other institutions (certification of trust). It establishes the credibility / legitimacy of the trust without a detailed description of what the trust does, exactly for the situation you ran into. IIRC it is only two pages and I was able to open a checking account for NFA purchase without any woke oversight or the credit union / bank having any idea what it is for.