Your estimates of spacing sound pretty good. I usually see between 1/8
and 1/4 between panels. If you were planning on installing an astragle
(spelling?) strip to cover the space between the doors, I'd go 1/4. If
after you have installed the doors, they touch. Pull a panel up snug to
the other and trace the line. Take the hinge pins out and set the door
up for your largest hand planer. Use the traced line as your guide to
bevel to. Or measure the distance from the edge to the mark and split
the bevel between the two panels. I'm that picky.You should find that
it is a very slight bevel, maybe 2 or 3 degrees. It will be a tighter
angle for more narrow doors.

Tom in KY, with a french door that needs planing in my own house.