I know I should avoid needing to do this where at all possible however are there any good join options for joining two plywood boards along their thin edge (rough cut with panel saw) for long distances? The goal would be for it to add minimal amount of thickness.

Sometimes I can design around this but other times when working with smaller bed areas I may end up needing to do this join small.

I am guessing 7mm is too thin for a biscuit joint and the inner material would betray me a bit here. I am also guessing that wood glue (even if I did manage to clamp this tightly) would not do me too well.

Any other ideas? Or is this just a bad idea in general?