I plan to sit the skids on a few inches of concrete blocks.
I built an 8x8 of similar design, and pulled it with my 20hp tractor.
Now then 8x12 is going to be 50% heavier, so not sure dragging it
around is going to be much of an option, but if I had to, then it
could be possible.
Planning 6' sidewall studs and a gambrel roof. I tend to sort of play
with the layout to optimize the standard building materials.
So it sounds like the 8' skids are fine; I also got that from a
reputable contractor I know.