Regarding road construction across wet soil…
 
It is not a DIY project, but it can be done. Irvine California does it all the time. It’s not pretty. (Note: Many years ago I worked as a soils inspector in Irvine and other problem areas for earth work construction.)
 
Whatever you do, do NOT use heavy equipment with rubber tires. (Your pickup truck is not “heavy equipment”. A backhoe is not. A dump truck is. An earthmover is.)
 
Rubber running over wet soil tends to create a pumping action that brings water to the surface and turns it to mush. It will not stabilize for weeks, so don’t let it happen in the first place.
 
Use track-based equipment. I suggest a bulldozer no heavier than a CAT D-6 (about 18 tons). Larger than that will need swamp tracks. The work will go slow. Sorry. If you try to hog this job out, you might bury your equipment to the axles.
 
Your job (as with any road) is to build a bridge across unstable soil. This is done normally by using aggregate base, but if you just pour the normal base onto this wet soil, the base will become saturated. The base itself will sink into the mud and be lost. You need something for the base to sit on at least long enough for the base to be compacted.
 
I suggest using chunks of concrete about 8 to 12 inches. I’ve seen larger pieces used but the idea is to crush the concrete pieces and push them into the wet soil, making the soil stable. You have seen this at the ocean where breakwaters are built using large stones. Have a track bulldozer rolling over the concrete and pushing it out. (Watch for rebar that will puncture dump truck tires.) Little by little, a truck-load at a time, you are building a bridge across the swamp.
 
Check this out with your local soils engineer, usually an older engineer. A younger engineer just out of college will lose his nut, but a guy or gal who has seen some crazy stuff work will think about it. If you can talk him into it, you will have earned the love of builders all around you. They are paying money out their butts dumping old concrete at the local dump. They will haul it to your site for free!
 
You are building a rough bridge. On this bridge you will lay the normal aggregate base and compact it. That creates a structure. If the base is moving, you don’t have a structure.
 
Alternatively you could mix cement (not concrete) with the soil and create soil cement. You could also mix cement in with the base. This is not a DIY project, but the bulldozer could probably do it. BUT, I have seen this fail causing weeks of delay before it can be tried again.
 
There is also a soil mesh than can be used to spread the load across the wider area. This is all done so that the base can be compacted.
 
I am only giving you hints. I left a lot of things out. You need an experienced road builder to make this happen if it can happen at all. I think it can, but a lot of it depends on the type of soil you have. Clay is the worst. Sand is the best. You can figure out the inbetween.
 
Good luck.
 
I mean that.