Thanks for the tarp idea. I did put a sheet of plastic over the hinge gap and that kept most of that area clean. The dirt guy was careful not to load it too far forward but the man with the mulch just dumped it all over.
It is almost worth renting a trailer just to avoid cleaning out the hinge area. I'm stubborn though and like to use a truck because I have a truck. Left it outside and now we had an unexpected ten minute downpour. I'm picturing all that gunk getting wet and settling in.
This morning I picked up a load of mulch. There is a bunch of it in the space between the cab and the bed. With my old Dodge Dakota I could just clean the gap with a leaf blower or even a broomstick for a bigger clod. I realize I should have stuffed an old blanket in the gap or even duct...