I picked up a good dual handle rivet squeezer set at Oshkosh this year. (pic 5) Riveted the pitot box nut plates together with the edge braces (L channel). Used the the box mount to line up the placement on the inside skin by starter punch through a few of the nutplate holes, then by marking the rest using the inspection cover (sharpie). (pic 1) After drilling out all of the nutplate holes to final size (5/16"), I placed the pitot box in place and cleco'd through the main spar hole that lined up with my mount brace (had to drill it out) and C-vice-gripped the other part of the mount to the rib. I lifted the wing with my left arm, and from the bottom of the wing, (pic 2) screwed the panel mount screws (using my rigth hand) through the nutplates in order to pull the pitot box up tight against the wing skin. This took a little longer than anticipated because I also had to re-run a tap through each hole and though the associated nutplate. Once done I set the wing back down and form the top-inside of the wing I drilled the corners of the access hole through the box (updrilled with step drill) and cut the rest of the pilot inspection hole out with my handy Olfa knife (pic 3). I then drilled out the pop rivet holes that I'll use to mount the pitot box to the wing skin perminently. Re-lifted the wing (arm is getting a little tired by this time) and removed all of the screws. Deburred, Cortec'd (corrosion protection) everything (pic 4), cleco'd back in place, relifted the wing again and riveted with my manual riveter (pic 6). I was really wishing at this point that I had enough room to move my table out of the way and put the wing on saw horses...but there was no room.