I'll start with 4, but expand to 8 of the GS100 panels from AMSolar. Not to be confused with other panels using a similar model number.
40.8"x20.7" = 844.59sqin, 17.7v, 5.7a = 100.89w: .1194w/sqin $280
which is the most per sqin I've seen so far. 14.5 pounds each
Of course, that's theoretical wattage in lab conditions, but 80% of the most is more than 80% of any other.
I thought for a long time about putting in the flex panels, but since I plan on hanging out in the northern US for a majority of the time, I need the ability to tilt the panels.
I'll need a charge controller outside of the range what GoPower provides, but will be using their 3000W pure sine inverter for sure.