Why not cosplay Kiki this year and give yourself more time to put together Mikasa? Some people will be critcal and others won't, that's life. I hate to see the work you put into Kiki's go to waste though.
I don't see why Kiki's would look odd in public as long as you weren't carrying the broom. As for the comfort issue, you can buy flats since you seem willing to spend some money (having to buy things for Mikasa) if it's a big concern.