I'm trying to think where on WA section I there would be a road crossing with a parking lot and restroom, about halfway along. It's been a few years since I walked that last but not that many. You're not talking about Ulrich Cabin??

Anyway, on topic ... :-)
I've done food caches, but always in bear canisters. Hiding them, definitely, a good few steps off the trail in places where no one has any reason to venture. By using an animal-proof container, I don't worry about keeping it too close to human-frequented places (quite the contrary). I also look for a shaded spot that's not likely to flood, that sort of thing.

A couple of things can go outside the can. If I'm also caching water (which sometimes makes sense), water bottle(s) of course. Possibly a fuel container of whatever sort. Even on occasion a clothing change can be nice, though in fact I've never bothered with that. A little charge unit to recharge my phone/camera. That leaves plenty of room generally in the can for just food.
I also find it wonderful to include a little food treat or two, something(s) that will hold up well in the forest, to be consumed on-the-spot, food I would never want to carry. So maybe a can of fruit, small bag of potato chips.

Maybe this is obvious already, but just in case ... if you do walk your cache a "good few steps" away from the trail, it's an excellent idea to snap a photo of the spot where you leave the trail, and voice record or otherwise record in essence a sort of pirate map set of directions to get back ("From the big rotting stump, 13 paces east-southeast to the micro-clearing ... ".

Despite hiding it (well), I too consider it good practice to leave a note on top of the can, giving basic contact info, date that I expect to return to pick up the can, and a friendly plea to anyone encountering the can to not leave me hungry and bereft. My approach to this is to write it on plain paper and then tape that on the can using wide clear packing tape, so it holds up well in the weather.

I've heard of people hanging their food as a cache, and I just --- wouldn't. I've heard of people burying a cache and --- ditto. My opinions, anyway.
Brian Lewis