"...worried about the safety of the person who pushes the second chock in place...". Really?
With your foot on the brake, nothing is going anywhere. Or, put it in "Park" before anyone puts chock in. Set the parking brake before releasing the foot brake, and nothing is going anywhere.
You take more risk towing to your campsite than placing the second chock, if you do either method above. I can't see risk, unless driver is totally unaware of other people, and does not keep foot on brake while leaving truck in-gear. Just my opinion.