I don’t know. Never seen that come up.
You shouldn’t need a gun trust for legal firearms, at least at the moment. Background checks still apply to the transfer, even for a gun trust. If a restraining order keeps you from possessing firearms, then you’d still be in possession, even if the trust owns it. And, a restraining order can probably be written to cover the trust’s ownership ... provided the writer knows about it (which they’d likely be able to find out).
SnakeDoc
You may want to spend some time thinking about this. As of right now, I don’t have any “illegal” firearms. However, that could change with the stroke of a pen at any time the other side gets one vote over half — and at any level of government. Would a trust, arranged before they became illegal, offer any protection from them from being confiscated (or ordered to be turned in)?