Here is the Hayes HDX off highway logging truck. Truck has options for multiple colour configs, front wheels, lights, and some other options. Trailer loads on the truck while empty and has a loading strap for lifting. Truck and trailer both have tripping bunks for dumping an entire load at once.

SimpleIC is required for the trip bunks to work. There is a trigger on either side of the bunk for the stake on the opposite side. I would suggest using a machine to push the logs off and building a small ramp for them to roll down. Enjoy!

Thanks to Mayto for the 12v71 sounds.