If you'll let me know the dimensions of this aircraft I'll look at designing a tail for it.

But as for a V tail what you are going to do is basically use the projection of the V-tail on to the different planes. Design a horizontal, and a verticle and then from those dimensions use the tangent function to find the angle and the pothagrean therm to find the span of the v-tail. Keep the choords the same just to simplify things. Be sure to get the angle right!!!

Nmking09