[JRTJH]

Let's look at the "whole picture" not just the drive or pulling through the mud.

First, there's the PVC frame on a 15'+ tall structure that's covered with a tarp. That may (or may not) survive the "winter winds" and the "summer sun". If it were me, I'd not install a $1000 drive to a $1000 building until I knew the building is going to survive the weather.

So, this is just a suggestion, but something to consider. You're concerned with pulling the trailer through the wet grass/mud. That happens only a short while, otherwise, there's no real problem with getting the trailer in and out.

Putting chains on a truck and hitching to a 4 ton trailer to pull it through the mud is going to make a "helluva" mess in the back yard. You are assured of having ruts at least a foot deep, provided you can even pull through the ruts.

I'd look at the weather forecast, and if you're expecting to use the trailer and rain is coming, I'd pull it out before the mud starts and park it somewhere you CAN get it out. Then, when the mud dries, put it back in the building.

Then, if in a year or so, the building is working as planned, that's the time to start building an expensive rock drive. If you invest in the gravel/limestone/granite now and find the building doesn't work as hoped, you're stuck with a lot of "stuff the lawn mower doesn't like".....

I'd slow down a bit and look at alternatives to the gravel drive for this year, then see if it's really needed once you know the building is going to still be there, "next year"......