Never mind how you look. Physically, it will be uncomfortable for you. I am 6'3" and rode a Rebel when I first took the MSF course. It was ridiculous. The handlebar ends were hitting my knees. There's just not enough space for a tall person.
Are you playing an electric guitar? The pickups may be "hearing" electronic noise generated by the computer. Try stepping back a few feet with the guitar and see if that helps.