I would have to see it in person, but I bet that there is a good chance that paint from your garage door will easily come off with some rubbing compound, followed by some polishing compound, and then some wax. At least then it will be pretty dent.
Right now it's at the point of being a pretty dent. The other option is to get a tank pad that covers the dent. I have seen some carbon fiber "style" tank pads that cover up to that edge and would disguise the dent reasonably well. There were a couple on eBay for~$50.00. There is another one that I might consider as well that actually wraps around the sides of the tank and would cover up the dent entirely. I'd have to see how it looked first before I committed to it. I know $50, is $450 less than a new tank, but I don't want to cover it up just to hide a dent and not like the look of the tank pad.