Ideas for How to Clean Gas Tank / Rear Skid Plate?

[vt_maverick]

Going to be doing a complete top-to-bottom detail tomorrow in preparation for our Wisconsin trip and was wondering if anyone had tips on how to clean the gas tank / skid plate area? Mine looks like this:



Honestly it doesn't look too bad between washings, but the contrast is really striking right after an application of Back to Black. I was thinking about trying engine degreaser first, but thought others might have ideas?

Thanks!