After long deliberation I finally decided to build a wing walk into the starboard wing. I figured that one day someone who's polluting the gene pool will not understand what 'No Step' means and climb up...
I made the triangular gussets slightly larger because after cutting out for the 1" x 1/2" support, there wasn't much material left at the necks of the gusset, 'not sure if it needed doing or not, but I felt more comfortable. I cut the notches on a table saw - nice and neat.
Tip: Make the gussets rectangular to start with, cut the notch then cut to a triangle. This gives you more handling area while fabricating.
The plans show that the 3/16th ply sits flush at the top of the ribs. Because I have 1/16th ply leading edges which cause a step down to the ribs, I decided to make the 3/16th up from: 1/8th ply, flush with the ribs as per plans, then veneer over everything including the ribs stations 21/4 and 131/4 with 1/16th ply. This flushes everything up to the leading edge ply.