I really don't like the idea, largely because of how much more expensive the Wraith miniatures are. What I would do is to make a single model Wraith head in a slightly smaller scale (or see if an Epic Wraithlord has an appropriately-sized head), and make a rubber mold for it. It should mold very easily since it would have little detail. Then you can use that head to convert either Aspect miniatures or Dark Eldar Warriors into smaller Wraith constructs. You'd have fewer issues with weapon sizes, base sizes, being harder to hide, and it would end up cheaper in the long run.