Maybe I am misunderstanding, but wouldn't the tongue jack landing pad just dig into the ground when you tried to drag it around? (Perhaps your trailer tongue is light enough to lift by hand???)
If you can't lift by hand (tough on backs anyway), seems like you will need something that can lift the tongue that is on one or more large wheels (wheeled tongue jack, hand truck, or ???).
Then you might need to put down a couple strips of thick plywood or 2x material that you can easily move as the trailer rotates to keep your tongue jack wheel(s) from sinking in the ground.
Keep in mind that if the spot isn't level, and you move the tongue to the low part, you will have to push it back uphill (ugh).
Beware of changing conditions that might cause the ground to become soft.
And don't forget that, if you use the winch, come-along, just a pulley system and your muscles, you will need an appropriate anchor for it (or a direction changing pulley) that is inline with the direction of pull. A tree, your truck, a dead man, or even many small bushes (if you know how to set up a load distributing anchor) can be used....but you will need something.
Great concept, and I look forward to hearing if you come up with a workable solution.
