Andrew,
It is nearly impossible to make a SHINP laser legal and if you could the cost of doing it would so vastly exceed your budget that it is not even worth considering. When we do development & compliance on our products - which are spec'ed appropriately from the beginning - it can cost upwards of $100K with $50K as a fairly common number and everyone once in a great while ~$10K if we get very, very lucky.
Secondly, the effect you describe is very dangerous with a high powered laser especially considering that burlesque venues typically do not have very tall ceilings as a proscenium theater might. The closer the performer is to the laser, the lower margin of error. Further, while I don't think you need quite as much power as Brad suggests under a variety of situations you are using laser in one of the least visually helpful ways possible. I shot a quick video to demonstrate the concept:
http://www.youtube.com/watch?v=f_rfZYP0ZZI
Doing a perpendicular shoot does require more power, which increases the hazard. I would find a different way of doing this my friend, perhaps with an LED.