Here's an update on the tank project.
I sanded it out some, rinsed it with acetone and got a second layer of fiberglass and epoxy on it today. One more layer to go.
At this point I can see I didn't leave enough room between the tanks so it's not going to fit on the frame. The fiberglass is building up pretty thick, but then that's what I want. This really isn't an issue because I'll just cut it down the middle and bond it together at the width it needs to be later. This will actually make it easier to finish the valley area underneath anyway.
Now in case someone is thinking this looks like a cheap and easy way to make a fuel tank, here are some things to ponder first:
1) I've worked with fiberglass for years and have a lot of experience with epoxy, too, but this is one of the more challenging shapes I've had to work with. I'd say this isn't a good project for a beginner.
2) All told - fiberglass mat (2 square yards), epoxy (one gallon), tank sealer, fairing compound, foam and fittings - the cost, not counting labor, is over $200.
3) In retrospect, I'd only consider doing this if I couldn't weld. I also have metal fabrication experience and now that I see how complicated this shape is to fiberglass, I would weld it together next time. It would be cheaper, too.
4) I do have to admit that I splurged on the fittings because I found some aluminum bungs and caps that look to be perfect, almost identical to Harley fittings from the 1910's, plus nifty anti-surge vents. I also picked up flanged aluminum fittings for the petcocks. That was about 1/2 the cost.
So this is fun and interesting and a little pricey, but it should yield a good looking and functional tank. But yeah, next time, steel.