You absolutely cannot prepare an accurate 1041 without having read the trust documents. A trustee who doesn't know that the trust has a filing requirement can't be relied upon to get any aspect of the tax treatment correct.

I agree with Susan - if no extension was filed, there are already two delinquent returns.

It would be one thing if they said, "here's every scrap of paper we have; feel free to talk to the attorney if that's not enough;" anyone can find themselves in a situation where they need a hand out of a hole. But this looks like a hole entirely of the trustee's making, where he's digging downwards as fast as possible.

"Here's your stuff; there's the door" is an entirely reasonable position for you to take. Just because they need a return, that doesn't mean you're the one who has to prepare it.