Flushed tank with hot water then blew out using heat gun in fuel fill hole and blowing out sender hole. Then swished acetone around and wiped out as good as i could reach with shop towel and long screwdrive with duct tape on end (about a 2' screwdriver).
I wiped down the entire outer side of the tank and cork-stripped it all the way around.
Temporarily inserted fuel sender and screwed it wdown until i get a day when it's either warm outside or when my wife isn't home to smell the sealant.
Dropped the tank into the wing (inserting the vent into the already drilled vent hole that I made the other day) and took out rib #3 to draw a marker line around where the drain hole needs to be.
I then took a scrap piece of aluminium and drilled the proper size hole as a guide and layed it over the mark i made on the leading edge skin inside and finished the circle made for the drain (I could only initially draw a small portion of it while the tank was in place).
I initially marked the center with a very sharp awl and then freehand drilled with the high speed drill with a #40 bit.
I then took my big stepdrill bit and opened it up to the proper size, afterwards cleaning up the edges with the hole-deburring tool.
A good day.