If you decide to drag it, I would suggest putting diagonal 1 x 6's from top front to bottom back screwed to the inside studs. Also put a 2 x runner across the skids at the back and diagonally brace the skids to keep them parallel, but more importantly, to keep one from leading the other when turning. This should give even pressure to the base to move it and the diagonals will keep the top from rocking back when starting the pull.
However, we moved one for my nephew last year (2 miles) that did not look in much better shape (but also not as tall) by putting 2 x 8's long-wise under it, two more nailed across at front and back, making a sled, and using 2" pipe and ramps, winched it onto a flat bed trailer. First step was pipes under shed (and two or more for adding as we moved it), then slid in 2 x8 s front to back on top of pipes. Jacked up shed and removed blocks and then lowered onto 2 x 8's. Then screwed front and back 2 x 8s down and then started winching it forward, up ramps and onto trailer. It helps if the ramp boards are offset to the 2 x 8's, as it allows you to get a pipe under them when starting it up the ramp. To connect to winch cable, we used heavy cargo straps that ran across the across the top of the longitudinal 2x8s, and under the cross tie ones. The worst part was when the front of the skid 2 x8s got up to the trailer, and we used the spare pipes that had rolled out to lever it up enough to clear the back of the trailer. Getting it off is a bit of excitement in itself, We dragged it using a second truck until we got the back edge on blocks, and then slowly pulled the trailer out from under it. Ramps must be attached to trailer for this to work.
Hope that made sense to you. Don't know if that shed's base will take that strain tho, (the one we moved had a fairly solid floor) as the 2 x8s do flex. If the ground is flat, I would drag it, either on the ground or using pipes to roll it.
Just some ideas to ponder.
Go
PS: While we were moving this trailer, I was wishing I had all the short 4 x 4's, 6 x 6s that we used to block up boats and trailers when working on them in FL. Lots easier to jack up and block, slide trailer underneath, and then reverse process at destination. For something as light as this shed, you could probably get by with concrete blocks and a couple of 5 ton bottle jacks. Wood is much safer as concrete blocks can shatter if something drops on them. Just make sure the "piers" are wider at the bottom, and are not just one block stacked on another. They need to crisscross, so that means at least 2 blocks for all but the top layer. The jacks have to be able to lift it higher than the thickness of the blocking material. Forgive me for stating the obvious, but have BTDT, and have cussed the need for 2 jacks and a stack of 2 x 4 scraps to get something up that last couple inches.
