Biggest thing is to shoot from a field position, or near it, if you can get your rest and bag in place and the rifle seated in under 10 seconds, and the rest and bag aren't hard to carry (and are something you'd normally carry in the field), I don't see why not. Personally, I shoot this match from my hunting daypack without a butt support (except the ground, if elevation allows, last year I can't remember), to keep in the spirit of a field shoot.
I'd like to avoid purpose built rests etc as much as possible, but they can be rationalized. Main purpose is to shoot the old army way.