Steve I am the queen of needing help to lift so here are some tips.
If you use 2x8 you can build a frame and put it on as siding. Many do with more than one sheet. Your frame can act as a backer just get the boards a bit wider. Not 1x2's and make it like a house.
You can put the spline in the bottom side and try to get the top to go over it, If your going to put them 2' vertical same thing. This will not be easy by yourself.
Steve F. had his swinging from the ceiling on at least one build.
I had trianglar boards I screwed to hold the sides up. You can, screw them on then rock your sides up. Once the door and windows are cut this is pretty easy. Screw them into the deck so the sides are square.
BTW--use thinner wood.
Here is a picture of the trial run with the blocking
My walls are 5'x10' and 3/8 thick. I needed help in this picture with no window yet. Having someone use the screw drive might help.
