Plastic outdoor chair cover from $2 shop (usually you buy 2 for $4 or $3 each, go figure for a $2 shop
), a little bit of duct tape in 3 places around the opening, hole punch through the tape, then loop large rubber bands through and onto the leg adjusters of the G11.
Dont forget a towel to put over the scope first to minimise dew build up effects underneath and stops the sharp edges cutting through the plastic.