As promised, I'll post some pics of my motoGP-inspired fuel tank.
First, I made a female mold out of fibreglass of the front section, which will be removed. You can't tell by the photo, but the inside surface is quite smooth, following the contours of the tank itself. The seam you can see towards the top of the mold is where I built up the area using electrical tape. This will be the "lip" that mounts to the remainder of the fuel tank.
Next, the modified tank itself. I wish I could lay claim to some of the workmanship, but I can't. The artists at Cycleboys did the work, even grinding smooth the welds at the joints.
So this is the new "front" of the tank. The modified tank was pressure tested to 5 psi, which should be plenty, as I think the fuel pump only draws at 3 psi. The gauge of the replacement piece is 18 ga, so slightly thicker than the stock tank material -- however the tank is noticeably lighter, as the front part of the stock tank had considerable material comprising it. A lot of teams mount the ECU under the tank cover, to keep it protected... perhaps mine can go here too?
This gives you a sense of what the finished product will look like... although remember that the fibreglass piece here is a female mold... the plan is to lay carbon fibre on the inside of it (after polishing the surface with mold release, like I did to the tank), and "pull" the male piece out. Not sure of the fuel capacity, but still plenty more than what is needed for a typical sprint race. The fuel is now retained in the centre part of the bike, closer to the C of G. I'm working on a front tank mount setup, utilizing the two tabs on each side of the tank -- you can see one just aft of the fibreglass mold.