maybe you could put the object on a narrow, higher stand and a use a higher corner (where the patterns are fixed with an offset to its bottom edges)? This should make it possible to put the laser below the cam.
....Don´t know if that might work with a planeless scan (for this is´nt a regular motion. Using RememberedPlanePoses might work - Anybody tried that?)
... but for a "normal" scan (or a window setup) you could try johnrpm's idea of putting the object and the corner above a horizontal mirror.
Now, sweeping the laser down onto the mirror, it reflects as if it would come from below:
Forgot to mention above:
To deal with different mesh densities in further virtual sculpting you could give SCULPTRIS a try:
Setting e.g the Draw brush's strength-value to zero and its detail-value (which is the mesh density value) to the wished value, brushing over the mesh its automatic tesselation (subdivision) only adds polys where the mesh owns a smaller density. (but to do that, the mesh´s size is limited (here about 500000 tris) depending on your machines muscles)