First, end-end would break in about a second.

I did a test glue up yesterday, end to end. Took it out of the clamp,
grabbed each end, and "snap" it popped apart at the seam... No surprise,
eh...

I wouldn't plane after the glue up. You're
asking for the piece to tear and explode in the planer.

Why? I routinely plane glued up panels and have never had a problem? For
that matter, I routinely run multiple boards simultaneously through the
planer without problems? Am I missing something here...?

If i HAD to do what you want to do, I would make a half lap joint.
the longer the better (more gluing area).

I'm currently experimenting with a scarf joint. Made up a quick jig to make
the scarf cuts on my miter saw. Will have to wait and see how that works
out...

Otherwise, I'll try the half lap approach.

Thanks!

Anthony