I hope you can post pics of your creation. My DH is into Harleys too and after we get settled from our move, that is on my ever growing list of projects to do!
I would guess that HD doesn't print fabric because they would lose control over licensing. They are very stringent on who gets to make "authentic HD clothing". I was going to buy a sheet too (they had them in the kids bedding at Wally World) but when I saw what they wanted for it I quickly changed my mind.