I'm there! I have my tank and I'm chompin' at the bit. If I have this correct, your plan is to drop the lollipop shaped piece in through the slice and weld it inside the tank like a shelf to avoid butt welding; great idea. You are the man! Keep posting,I don't want to miss a trick. Wonder if you're planning on doing anything with the seam?
check out the fenders I did on the two triumph choppers in my photo gallery "Triumph Twins" the raw fender is $29 and the fab is a walk in the park for a guy with your talent. If you're interested I'll give you the run down.
Paul

Strangler