I ALWAYS self assemble my ASW-20b with a (1) man rig (20 year old
Cobra unit). Works find and just about as fast 2 people. Like UH
says, it will take you a few times to find the tricks but my technique
is:

0. Make sure fuselage if perfectly vertical!
1. right wing first. need to find the correct height for your wing
stand. I never change the height or location for the wing stand.
Before leaving the right wing, I pickup the tip (off the stand) and
gently rock fore/aft to make sure the wing is squarely seated on the
drag pins. If it is not, you will never get the main pins in.
2. Left wing on. Same drill, make sure squarely seated on drag pins.
I also "know" the approximate correct wing dolly height (Actually, I
almost never move my wing dolly height.
3. Crank fuselage ramp dolly jacks up/down to get (1) pin in (hard
part) then tweak jack for 2nd pin,

Total time less than 5 minutes for both wings. On good days, about 2
minutes.

Disassemble: Nothing other than the ramp should have moved, so put it
back where it was and the main pins should slide right out. I pull
BOTH pins at ONCE in one quick turn and pull motion. Total time to
pull pins and return both wings to trailer: 2 minutes 11.5 seconds
(approx)

ST