I asked the fine folks at MDC and I was told that the hump is a cover for a fuel pump in the main float. That said, having hunted through the Kagero title, I could not find a single photo with it - and there are dozens of Rufe photos that I have never seen before included in that title. In fact, all the photos clearly show a clean float.
PM me your email and I'll share a copy with you.
I hate to be the bearer of bad news - but the turtle deck under the canopy is black. It will be our little secret though.