Pencil sketching while camping

On a quiet afternoon, I sat at the picnic table next to our campsite and started sketching the tree-lined meadow. After I got about halfway through my sketch, though, I realized that I was smudging my drawing a lot. I had started on the left side of my sketchbook, and was working my way to the right, but the problem is I am left handed!
Normally I would just grab a scrap piece of paper to put under my hand to solve this problem, but I didn't have anything convenient since I was out camping. I did eventually find some paper that would work, but it was considerably later in the day and the lighting had changed so I figured I would add to the sketch from a different perspective. Having covered up the first part so it wouldn't smudge anymore, I continued my drawing. I realized later that the tent was way too big and thetwo sketches just didn't quite fit together...oh well.