Extending the wires would be fine, as long as you solder and heat shrink them. I would not in any circumstance suggest using a butt-splice. BUT if you do that, after they said it was a no-no, unless you do it like they said, it would most likely void the warranty. I understand why the guy said to extend from the end, leaving the fuse link close to the charger, but I don't understand why you'd need another fuse link at the battery. You'd want the fuse link close to the charger in case you got a short in the wire close to the battery. It would protect the charger.