Greetings from Sacramento, CA!
Been a lurking here for about half a year and have been riding the 66cc kits for a while meow. Somehow haven't trashed my bike despite the blood, sweat, and tears I've put into it.
Also, believe it or not that rear gas tank is solid. I went though three normal tanks that would all leak after a couple hundred miles. So I invested in a rear-rack gas tank. It was also cheap ****, see for yourself:
Thankfully I was going less than twenty mph so the rack folding on the tire didn't kill me.