Apparently the v2.2 board is completely isolated from the housing. The v3 board however is not.This may be the sole reason people arn't having problems with the v2.2 board, but do with the v3 board.I'd be weary about just the undercoating as protection, if you have metal screws clamping it down (over time it may ground out).
Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician