Well, at $43.97 cents a sheet,( can you believe that? ) and increasing daily, plywood may not be the best thing. Besides, loaded tandems will turn plywood into toothpicks. I'd just find a better spot.
Been doing the plywood thing for years with no problems. Takes a few years for the sheets to rot out. We’ve got five old trailers that sit 9 or 10 months out of the year. They are on dirt and grass. Two of the vans a ‘48 and a ‘40 both with the tandems all the way back are stuffed full of old truck and car parts. Cabs, engines,trans,rears, and everything in between. The plywood helps with 3 things. keeps them from sinking down in the ground. Keeps the dirt from drying out the rubber on the tire treads. Helps keep tall weeds from going up around the tandems. We drop the dollies down on RR ties for extra support as well. Never had to dig one out and we get hurricanes and flash flood rains on occasion down here.
Ohh boy I remember midnight when I tried to back up into the grass and ended up in a dam ditch cuz that grass had a nice water thing going on for the farm and another time after it rained I got stuck my honest advice stay the #### away from the grass!! Lol unless it’s dry as hell outside
Compaction is everything; if it is used to park rigs you should be OK but watch out for sites with a lot of 'fill'. Years ago CLTL had a terminal on a customer's property. Turns out to have been their former dump. We had a strip of concrete running the entire length of the property to support the landing gear. A loaded trailer would, without the concrete, punch it's way into the ground within 5 minutes of being dropped. Never had any problems with the trailer tandems though.