I picked one of these up a couple of months ago on Amazon, they'd be great for chucking a pack on if you want a lightweight option for short distances. They'll need a bit of fettling to add some straps, but for the weight and size when rolled up they might be a better option than the loaded tarps I've seen.
Around 350g and a good size to take a pack or two, rolls up into a 18x3" tube
http://www.pelicansport.com/en/products/winter-toys/carpet/snow-flite-54
Around 350g and a good size to take a pack or two, rolls up into a 18x3" tube
http://www.pelicansport.com/en/products/winter-toys/carpet/snow-flite-54