There are others with far more experience than me, but being as you're probably feeling pressured on time, I'll chime in.
Leaving them in an enclosed bed with only the bed window open may overheat them. I would suggest lowering the tailgate at dawn and make sure the entrance is facing outward so they can come and go without issue and get better ventilation. If they need to stay in there overnight again until you finish the fence to keep bears out, I would close the tailgate up after dark and repeat this as necessary until your fence is up. When you're ready for placement in the yard, wait until after dark so all the bees have returned home for the night, close the entrance and move the hive into its final place. Open the entrance after its in place. You'll likely see lots of orientation flights in the morning as they learn the new hive position. I'm not sure how attuned they would be after reorienting, but since it's in the immediate area, you may want to move the truck under a covering, put a cover on it, or move it in a garage to avoid confusion of the bees if they see it from the air since they recently used it as reference for home. I certainly wouldn't park it back in the same place as you may lose bees. Just some food for thought. Other's may have better suggestions, but I hope you find this of some help in the meantime.