If you want my advice, don't bother with a chessboard bandanna: make 6 laminated Eeyore's wedges at a scale that fits your bag.
http://www.ee0r.com/tri-chess/index.html
Then you can play 2-6-player Martian Chess, still make a (somewhat wonky) chessboard, and even do other games (ex: Martian Frisbees) by laying out appropriate wedges and quickly marking out the board border with a wet-erase marker.