I think doing duels on here would be a bit difficult,i would rather have it more random, so maybe use Proxies on dueling network (using a card, but having it stand in place of the card you actually want there, aka using a flamvell magician, but having it be the proxy for some monster you came up with)
Also, there are some dueling programs that allow custom card creation, but i cant recall the names of them, one is more like Devpro, but i have never actually used the interface, the other is sort of like DN, with it being browser based, but the sign up was not working. so proxies may be the best bet. 
doing duels on here could result in perfect plays and mass cheating, with a program its actually fun, random, and not tedious.
trust me, i know the tediousness of writing out a duel (i am writing a Yu-Gi-Oh! Fanfic.)