Bottom wing skins: pitot mount and flap gap fairing riveting

I replaced the bad rivets behind the inboard bottom wing skin with CR3212s (and one CR3242) as recommended by Van's, for much better results:
Inboard flap gap fairing rivets re-done with CherryMax
I also used MSP-42s for the other rivets that would be nearly impossible to reach with a bucking bar:
Pop rivets for the inboard portion of the flap gap fairing
Pop rivets for the inboard portion of the flap gap fairing
as well as the rivet that sits too close to the bracket from SB16-03-28 (which Van's was very kind to address during the quickbuild process, but left me without access to buck that rivet):
Pop rivets near the SB16-03-28 bracket
My OCD side dislikes having two types of rivets on the same line, but there's no way I'm going to remove and re-set all the solid rivets :)

I then continued with the Gretz pitot mount installation by match-drilling 3 of the backing plate holes through the skin from the inside, which was annoying and required 2 people - one with the drill and another with a mirror to position the drill bit into the hole using a mirror:
Finding pitot mount backing plate hole positions from the inside with a mirror
Pitot mount backing plate match-drilled to skin from the inside
With the two holes near the rib, I positioned the rib bracket against the backing plate and rib (using the mirror to get the right height), then match-drilled again through it. I removed the skin and match-drilled the other 2 holes of the bracket through the backing plate and the 3 1/8" holes through the rib:
Rib bracket match-drilled to backing plate
I clecoed the backing plate to the skin again, match-drilled the remaining holes and marked the main mast hole:
Gretz pitot mount backing plate match-drilled to skin
To cut off the mast hole, I then used the Swiss technique - drill it like a Swiss cheese :)
Mast hole marked
"Swiss cheese" of holes to cut off the mast hole
I then finished it off with the dremel (cutting and then grinding), through the skin as well as backing plate and washer plate (which I had to trim down for the rib bracket to fit):
Main section of the mast hole removed
Backing plate and trimmed washer plate also grinded down to fit the mast
Gretz pitot mount in plate
Gretz pitot mount in place
I then test-fit it again in the wing, and also determined that there's enough wire in the heat regulator box to reach it from a couple of ribs inboard (which is good to minimize interference with the NAV antenna and magnetometer on the wingtip):
Wires from pitot heat regulator to pitot tube
I also drilled and deburred the other cover plates:
Drilled and deburred cover plates
It was then time to deburr the hundreds of holes on the bottom skins, as well as their edges and the corresponding holes on the ribs - no photos of that, but it's most of the time in the time lapse below.

Time lapse:

Total bottom skins time: 34.9h
Total bottom skins rivets: 406

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