Want to pitch your tarp sides touching the ground for winter protection? You pretty much have to have a structural ridge line to do so unless the trees are precisely positioned for your particular rig. In most instances, you will need to keep the straps rather low on the trees with a shallow angle from the straps to the hammock, so that the suspension doesn't interfere with the tarp ends. To accomplish the low strap suspension and shallow hanging angle, you pretty much must use a structural ridge line so you can pull the suspension pretty tight to keep it below the top ends of the tarp without the bottom of the hammock hitting the ground.
If you are considering winter hanging and don't have a structural ridge line, I strongly recommend adding one before you begin your winter hanging experiements. I've been out for about a dozen winter nights in the recent past with my tarp pitched directly to the ground on the sides, and the only way I can make this work is by counting on my structural ridge line to keep the sag at the proper angle. Get some zing-it for the structural ridge line. Quick, easy, ultralight.