What do you mean by "spiral vee?" As I know it, a spiral vee is term used for double concaved vee bottoms where the double concaves run right out the back, and don't go to flat or panel vee behind the trailing fin. On swallow tails that type of bottom is sometimes called a "double barrel." But yea... it's done.
A vee out the back is usually a panel vee, with flat panels. That's not a spiral vee. That's just, "vee out the back." A spiral vee has to have concaves, and it was originally used on rounded pins, but can be applied to pretty much any tail shape.