Could you use a bread tin as a pate mould?
I've used a small loaf pan as a pate mold, worked just fine. I don't see any reason really not to use one as long as the size is good for what you intend.

I don't like the plastic wrap idea, I'm not interested in cooking with plastic in a high temp environment. With sous vide you know that temps aren't going to get above a certain temp but in the oven I'm not convinced that the edges of the wrap won't heat to a point where it's breaking down. Typically when I do a pate I'll use thin sliced bacon to line the pan which presents a non-stick layer as well as some flavor. More traditional is the use of caul fat which is a thin sheet of fat that surrounds the stomach if I am remembering correctly.