I've taken dry spaghetti sauce before, but they all seem to require tomato paste ... which I would dehydrate anyway.  So there is not much upside when you can just dehydrate the off-the-shelf spaghetti sauce.

However, unless your taste buds are set on a tomato-based sauce, you could go with a pesto sauce.  Some dry ones are pretty descent and you'll only need oil and water ... plus the prep time is near zero.  I've used pesto on tortellini, pasta shells and orzo ... not bad on any of them.

dd