When cruising in tideless areas, many of us either put the bow of the boat on the beach (sand), or stern almost to the beach--in a few inches of water. There is some danger to the trim tabs, and transducers if the boat's stern is pushed against beach or rocks.
If I was in AK, and wanted to 'beach" the boat, I might put the bow on the beach for a short time, maybe unload, but I would get the boat back out into deep water (I use a rig, where I drop an anchor over 100 feet off the beach, set it, then have a block on the end of the anchor rode, and can pull the bow of the boat out into deep water, and secure this 'endless' line on to a tree or rocks on the shore. One has to be careful, in areas of 20 foot plus tides. You can not only leave the boat high and dry, or you can put the place where you tied up a bow line, under some very cold water.
All of the cored bottoms can be beached--the plywood, the balsa and the foam core--nothing magical about the core. Most of the C Dory are solid glass from about the windshield on forward. The pre 1987 boats may have plywood core further forward.
You never want to let rocks or even sand abrade the bottom of the boat to the extent it might jeprodize the core. The outer glass is about 1/4" thick--it can vary. All of the hull designs are gong to be easy to beach.