I've already joined my pieces and have begun bevelling the edges (largely with a plane, but the ends take to a rasp a bit easier).
I'm suddenly consumed with paranoia I've bevelled the wrong way, and I just want to verify things are ok. Perhaps because I'm a lefty I sometimes find I do things a backwards, and the text isn't very wordy about this step.
I've laid the panels fiberglass tape side up and held the plane 45 degrees inward toward the board, thus the tape side height of the panel is narrowed by the bevel, and the outside height of the panel is unchanged. Ends take more of a 33 degree ish, but again, all inward.
To do otherwise would actually require you to hold the plane on the underside, so I don't see how I could be wrong, but again, just checking. All is well?