Label them as what they are and make it very clear they are crosses. The visual differences and how some look like one species and some another are exactly why some people (myself included) don't like the idea of crossing them. You know they are crosses, but what if they baby you have up gets resold as a Sumatran Short Tail (black blood)? You have no control of what happens after they leave your hands. I have now become very very cautious with my short tail purchases - while I'd like to be able to trust small breeders, I don't know that I'll be able to anymore because of the sheer numbers of crosses being produced and sold by the few that do it...