i think if you wanna think big you should promote the GT logo..
for example, if you have the GT logo say 5cm long at the front on the side (chest height) and 20cm with gtpopping.com on the back, or vice versa. this will give your logo identity and the next T-shirt could only have the GT on it.
by the way i like number one... keep it simple.
Just a thought.
Tony