We have recently bought a Soulpad with a zippable groundsheet. Our neighbour has said that a lot of campsites don't allow groundsheets as they ruin the grass and you have to have special eco ones that are breatheable. I've been checking the t&cs of some sites we like the look of, but there's no mention of this anywhere. Has anyone come across this rule? This is our first tent, so we're a bit confused!