I had a moment to sneak out to the garage over lunch today, and started the rudder tip.
I had previously matchdrilled the tip to #40, but needed to upsize it to 19/64″ which is the right size for a #6 screw (and subsequent dimple or countersink).
Here I am halfway through the upsizing.

This is a post-dimpled picture, but you can see the CS4-4 rivet I am using in the last aft-most hole of the rudder tip. There is no way to get nutplates in there, so I’m filling the hole with a pulled rivet.
Some builders will epoxy a #6 screw head in that dimple so it looks like the rest of the screws, but I’m afraid I would try to screw it out in a few years when I forgot what I did.

To acommodate the shop head of the pulled rivet, I got the dremel out and notched the flange of the tip.
Please note, this was not enough of a notch, i needed to go another 1/8″ deeper, but didn’t take a picture.

Only 0.5 hours today, but I managed to set FOUR rivets.