Pulled off ply, and the RTV had done nicely, with only a couple of smudges on the fg, which sanded off easily. Crappy tape had fallen off everywhere else, so put a new strip of better tape on and clamped on the ply strips over RTV.
Fixed all the strips in position with bondo. Taped up the forward edge with 'Uni-Mask', masking tape with flimsy clear plastic mask attached.
Looked like there was a small gap between the shear web and the ply strips, so filled it with some iron-on melamine.