Rivets sizes
I have found many a place on my RV where the plans rivet call out seemed too short. As long as you can drive them correctly, a little long beats a little short.
I have a very nice gauge made by Clear Air. I tend to spec each rivet spot as I go and use the right one, as opposed to the plans call out. This is especially true if you (for instance) use camlocs on the cowling instead of the stock hinges.
For me, the goal is always structural integrity.
Regard,
Michael Wynn
RV 8 Finishing
San Ramon, CA