Sure, put a Titan in there. they get really really big!!! AND! they eat live rock, if you want a tank with sand then its ok, but if you add rock its gonna be gone.
If you have an open back canopy mount it on top of the canopy, if it is a closed back canopy put it on the outside of the back. just make sure that it wont collect any salt creep. I have a closed back canopy and mounted it on the back and havent had a problem yet. HTH.