Funny you mention glass breaking from vibration- have you picked up any chopper magazines lately? It's the new trend. Glass float bowls, glass velocity stacks, glass portholes in fuel and oil tanks.... And if you think our old bikes vibrate, sit on a shovelhead at idle some time. Lol. Not arguing, just noting that with some proper preparation, like some soft rubber mounting, it can be done. But I agree, it's risky. All it takes is a stone getting kicked up from the road and there goes your complete oil supply.