Crom, I was thinking of using a 10x14 tarp as a footprint for my 10x10 but I've heard that if you use a larger ground cloth that water will either pool, splash all over your tent and/or allow water to get between the tent and tarp. Have you found any of these issues to be true? I live in the southeast so I can expect rain anytime I camp.
I do like how it creates a porch for you though. The camo mat that I have in my photo above is an old nylon poncho liner that I can stake out. Because its nylon it dries quick and super easy to clean off.