In some states (as an American I always assume you are in the USA), its not as easy to get a license to perform weddings. I know that when I was a Secretary, I helped a MS get a marriage license and I had to write a letter signed by the entire BOE that essentially said that we recognized him as a minister in our local congregation. So, if the BOE is against the wedding, you likely won't get that kind of assistance. Of course, if the person you have in mind is already authorized by the local officials, then not a problem.
You can always find a secular official to do the actual vows then have a religious ceremony if you really want a JW marriage talk.