Step 5: Move, Or Have It Moved
If you're smart, congratulations: you've already got a slab or some easy foundation set up and can just have your new building dropped off perfectly. If you're like me, you haven't planned enough and will want to quickly scrounge some thick round material (think telephone poles) to set the container on for easier future adjustments. I used ~6" diameter round wood poles.
If you're going to fully move this trailer yourself or want to keep it portable, you're going to be entering the world of flatbed trailers. 16' utility flatbeds might be a feasible option for 20-footers, and they appear to be widely available on craigslist for ~$1,200. There are also DIY kits for the braver and old car parts for the truly hardcore.
Winches, come-alongs, and any other mechanical helpers will be your best friends during this process and later adjustments. Ideally, anchor to something much stronger than this tree stump and use the strongest electric winch you can get your hands on.