The coating doesn't seem to be quite as thick. Perhaps a few coats of whiteboard conditioner before starting and at intervals would help.
If you don't put a faux border on it, then you get whiteboard ink dust on the walls and it looks kind of trashy. I speculate that your best bet would be to get a bunch of trim with a rabbet in the back, bolt the bottom piece to the wall, have someone hold the board in place while you bolt the top part on to keep it from shifting. Hide a couple of screws through the boards along the sides to make sure it doesn't buckle on you.
https://www.lowes.com/pd/Broan-Universal-Backsplash-Plate-Wh...
Anytime I've bought them in the past, I just walked into a Home Depot and asked for "shower board, marker board, the cheap laminated particle wood". There are typically a few types, more like a board, so I ask for the flimsy ones used for cheap showers, and they take me to a stack of them in the lumber area. They are very thin, like an eighth of an inch. You'll need a vehicle larger than a sedan, BTW, this are BIG. But you can also have them cut for you, often no charge.