Banger, you are correct that trusts must possess property at the time of their creation in order to be valid. That property can be cash, ammunition, rifles, etc. the nice thing about a bank account is it offers a nice, verifiable way to prove the trust was funded at its creation in a way that is admissible.
As to what the best way would be, that is really a question for whoever drafted it. A trust is a complete document. Depending on how it is written, changes in one part of the trust may have unintended effects on the other aspects of the trust.