Plans have you do Layup #4 before installing the lower Winglet, but the wing is the right way up now, and I'd like to do it whilst my IRBH ponderings are fresh in my mind.
Started shaping right lower Winglet to match its mounting point, leaving a hollow for the floor of the IRBH pocket. Hot glue a couple of mixing stick to the upper Winglet for orientation.
Note that I need to build up the relieved area over the Bellhorn, so glue on a bit of wing foam with urethane bond, clamping with an old taped jig and rubber bands to the cleco.
Ripping off the peel ply. Love this bit.
Peer into the cavity, grind off where it touches, repeat.