cat litter or gravel

well today I tried to back up to the fifth wheel and the roads in our storage area is gravel but there is about 15 feet between the road to the trailer that is grass and just the slightest angel, well now its 2 tracks of mud, next month we are pulling it out of storage and I was thinking about laying down something in my wheel path to get some grip for the tires to grab, a little background, we live in Seattle so the ground is not going to be any dryer next month, the truck is a 1999 4 door freightliner weighing in at 12,000 pounds, it has an air locker and new aggressive street tires in the back, I was even considering buying a set of chains for the back tires, but that's a big expense and a lot of work for the 15 feet, so what would you do ?