I just got married this past May and wanted Bandit in it, but the place had peacocks so they didn't allow dogs. I tried explaining to them that he's 4.5 pounds and scared of everything, but they still said no. I even bought him a cheap little tux at Build-A-Bear lol.
I think it'd be a great idea to have him in your wedding. Just see if you can put his crate somewhere after the ceremony and designate someone to take care of him so you don't have to worry about that when your minds going crazy with actually getting married lol