a better solution would be to upgrade to, and integrate PhysX3.3, as other engines did.
and a lot of collision problems could be avoided by integrating the Recast/Detour navmesh pathfinder, as other engines did (nearly finished by WJBender's Peragro plugin). this will prevent from a lot of useless collision with level surfaces, when movement is allowed only on navmesh surfaces. it would also result in much easier enemy AI creation.
but it would require investing some time...
+1
If you aren't going to add any additional shape to OBB, then at least upgrade physX. There is almost finished plugin made by 3dgs_snake. Recast/Detour navmesh pathfinder will also be a great help!
Greets
