Well, don't force her to do whatever you want to satisfy your question. Some girls will not want to satisfy fetishes, so if she is one of those people, just keep it in you fantasies.
As far as insane, no. I have seen a lot of far past perverted fetishes on here. Fetishes are healthy more than anything, as long as they are not forced on to someone.
I have a shoe/foot fetish, and I never push anyone into it. Most girls don't think it is perverted, but just aren't willing to participate in it.
Don't worry, you will find someone to satisfy this fetish for you eventually. Assuming you get married, she will probably fulfill your fetish.
For now, keep it within her comfort level, and keep the rest in your fantasies. You don't want to lose her by pushing her into this one.
I have a fetish too.