I would approach it this way. I would taper the tiers and use modelling chocolate for the wrapper. I would roll “snakes” to get the ridges then wrap it. The benefit of modelling chocolate is it doesn’t dry as quick as fondant so you can work on the smoothing longer and you’d be able to smooth the seam. You could use fondant on the swirl. That’s how I iced the cake in this link http://cakecentral.com/gallery/2250607/giant-cupcake. Jessicakes has a tutorial for the wrapper here http://jessicakesblog.blogspot.co.uk/2011/07/giant-cupcake-tutorial.html
