Can’t speak on behalf of silencer shop trusts or what they require, but your town office should be able to notarize it for you.
I had a trust done about 10 years ago when I lived in another state. When I moved here I had it updated with my new county info as well as my personal info such as marriage, beneficiaries, and the roles of different people.
My town office notarized each part as well as provided witnesses at no charge,