I always use straw/hay to mate ... If they cold they will ruffle it up and climb under and if they hot they lie on top ..
BTW surely that rope cant be comfy i think more people should consider my idea .. it works like a dream and sometimes you forget you even have it on your back + when you bend over it doesnt come swinging round your neck at 50 mph and nock your dog out ...
PICS BELOW !! V V V