Occlusion check for up to 8 Projectors

once again i come here to humbly request your aid.

I am am working on a project where a complex model of a person has to be textured in real-time using the images from 6-8 cameras.
So far it looks quite good, the only thing left to do is to remove some artifacts. For instance, when the person holds up a hand in front of the body, the texture gets projected both on the hand as well as the body itself.

I am using projective texturing, so i already perform all the calculations to get the distance of a fragment from each camera. But, i cant use seperate shadow maps since i dont have enough texture units available.
I could use the alpha channel of the textures for depth information, but i cant figure out a good way to put the data there.

Is it possible to have a seperate depthbuffer for each camera so i can check for occlusion in the rendering pass?
Or maybe to output depth information directly into the alphachannel of my camera textures?

For this, GF 7300 (almost your model)

Max. texture coords 8
Max. tex. image units 16

So you can have 2 different textures (color and depth from a single camera) with 1 tex coords , and support up to 8 camera.