If you aren't planning on seeing it all the way through, don't breed them in the first place.
Breeding a CT to a VT has no real purpose, as the VT will be dominant and none of the offspring will be suitable for a breeding program (as you could just buy a new breeding pair and be way better off than attempting to imrpove your line)
However, if you really were just interested in breeding to see how it works or if you could do it, and were willing to do the work to see it through, there is nothing wrong with getting two VT's and spawning them. The IBC doesn't look down on people that do that, we just don't show VT's anymore. Most of us are too concerned with our fancy betta lines =P. In fact there is a rather raging debate going on at the moment about how we're at risk of losing some of the old, pure lines because nobody seems itnerested in maintaining them, and everybody is going after the marbles and the bf's etc. but that's another discussion.
VT's are very easy to get to breed, and you can almost always sell the offspring to a LFS (for cheap, granted) once they reach a sexable age.
. I might try to find a female crowntail, but I doubt they sell them at LFS like they do the males. Plus it will be good practice for when I start breeding more relevent breeds in a few years like I plan on doing.