Yes, I did, and the pictures I posted were ugly, but that was before I cleaned it up a bunch. Anyways, it's still under the backseat and I'm not anal about my V being perfect. I bought it used and it was never perfect, but that's my personal choice.
Cutting the hole is not hard to do, the metal is thin and soft to cut through, and you can easily make a sheet metal panel to cover the hole when you're done. In my case, I didn't replace it to upgrade the pump, I had an electrical issue that I want to keep an eye on. For that reason, dropping the tank would have allowed to me fix the problem, but it is extremely unrealistic to drop the tank every couple of weeks to keep an eye on a problem that could potentially return.