You forgot about the most important parts when decsribing MKR: The (sort of) giant robots and the fact that everybody and everything not from earth is named after a car or something car-related. (With the exception of Rayearth and Mokona).
I would suggest putting a crossover simply into the second part (MKR II) or after the end of the series. There really is not enough room for an inserted charcter in the first part. Giving him the knowledge of the true nature of Cephiro and the pillar would IMHO be a copout.
Then again if he can't play the magical omniscient problem solver, he would have to contend with the giant fighting machines (is there a giant-robot song?) and deal with the making-enemies-into-friends-instead-of-just-killing-them part. Not anything where Doug wold have to add much to what the Magic-Kights already could accomplish without him.
I would suggest putting a crossover simply into the second part (MKR II) or after the end of the series. There really is not enough room for an inserted charcter in the first part. Giving him the knowledge of the true nature of Cephiro and the pillar would IMHO be a copout.
Then again if he can't play the magical omniscient problem solver, he would have to contend with the giant fighting machines (is there a giant-robot song?) and deal with the making-enemies-into-friends-instead-of-just-killing-them part. Not anything where Doug wold have to add much to what the Magic-Kights already could accomplish without him.