I actually carry a regular 22.5" Weber. I pop the legs off the bottom, pull the cover over it and set the whole thing in a belly box.
HOWEVER ;)
More often than not, the campsites we hit all seem to be equiped with the forever popular tire rim for a fire pit. And they're all 22.5" tire rims :) Notice something familiar there?
I have 2 extra Weber cooking grate/grills, and 2 extra charcoal grates, both available individually for about $10 ea. All the hardware stores carry them as replacement parts. I take 3 bricks, place them around the edge of the inside of the firepit, put one of the charcoal grates on the bricks, and that holds my charcoal. Then I just put the grill on top of the fire ring, and we're good to go ;)
And...when I'm done cooking?...take the grill off, and pile it with firewood for the evening. Already has a nice bed of coals, and the bricks keep everything up off the ground so the fire can get plenty of air.
This is a VERY quick, easy, cheap way to grill where ever there's a "fire ring" :)
I still carry the Weber kettle, because sometimes I like to smoke some ribs, or a pork roast, or a chicken or two, and the Weber kettle is excellent for smoking.
Jim