I would just park anywhere north of Houghton/Hancock and ride your sled up to Copper Harbor and back. There is really no reason to drive up there and start riding.
Great parking spot under the lift bridge in Houghton right on the trail. Park the truck and trailer there and ride up to CH.
My goal is always to get my but out of the truck as soon as possible and ride to your destination. I am always amazed to find any trailers in Copper Harbor. Minimal pack= maximum riding!