I'm not sure. I think having a quirky piece of music is great, but I certainly wouldn't want a complete theme including Star Wars costumes and Yoda cake or whatever. Too much is definitely tacky. What I really cringe at is weddings where some generic overly schmaltzy first dance song is played, with the couple shuffling awkwardly across the floor, and poems, readings or hymns that seem to have no thought in them. I like it when the couple show a little part of what really means something to them. OP, If you've made your mind up I think your issue is more practical, and whether or not the Priest will allow your choice. Let us know how it goes down! 
On a side note, one song I've heard a lot at weddings lately is Marry You by Bruno Mars. I will tell you why this is an awful choice:
It's a beautiful night
We're looking for something dumb to do
Hey baby
I think I wanna marry you
Is it the look in your eyes
Or is it this dancing juice?
Who cares, baby
I think I wanna marry you
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"...something dumb to do" = I haven't given much thought to this at all. We've probably only just met.
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"...is it this dancing juice? Who cares, baby" = We're obviously wasted, confirming all of the above.
I genuinely want to know if people choose this because of the catchy melody and chimes in it, or if the lyrics really resonate with them and is a true reflection of their love! Cringe cringe cringe cringe cringe!