I have a kilt in the Cladish tartan from USAK http://www.usakilts.com/store/cas_kiltpage.php that I am very fond of, so your Browns tartan looks great. Although I do like the suggestion of adding the green line for the grass/astroturf. But I say go for it! Living near Knoxville, I do know that there is a Volunteer (UT Knoxville) tartan, so why not some NFL tartans?