I borrowed my Dad's one at Le Man's to (try!) capture a few light trails on the curves and it was marginal at best. Dont know what model it was, but it was about 10 inches high. The legs were wrapped around a scaffolding pole and just held the weight of my 7D and 17-55 2.8 but the head adjuster couldn't hold the weight - had to steady it with my hand. It won't give the stability of a traditional tripod.
The flexible legs of the GorillaPod is very useful, I'd take your camera and lens to a shop and try a larger model to confirm it'll take the weight. You could also try one of the new mini tripod's from Manfrotto?