As is I can adjust my leg position to not hit them, but they are definitely in the way. With a layback seatpost and shortening the length of the tanks a bit, there may be just enough clearance.
I found a moped tank on the mopedarmy forums that may work, so hopefully it will be shipped soon so I can see. Otherwise, I think I will start planning this build "for real".
I made some rounded endcaps from styrofoam balls and definitely like the look better. They make the tanks longer, so the main tanks would end up being shorter on the real build. It looks like you can get weld-on domed endcaps in this size for about $5 each online.