[Legbreaker]

It's worth running the same exercise with both tanks in hull down positions. In other words any Hull hit is a miss (unless it's a turret hit first which is converted to hull damage on the table).
Something else to think about is requiring the vehicle commander to roll an Observation check before the vehicle can react to the enemy. A half blind commander (usually the only one with their head out and able to properly see the surroundings) is pretty much a death sentence for the vehicle.

Something else to consider is how hard it is for the commander (or other crew in a position to see) to spot infantry in cover/concealment. Although an anti-tank missile usually kicks up a hell of a backblast and is damn near impossible to avoid spotting, it usually only takes one hit to take out, or at least badly shake up the vehicle and it's crew. Added to that, AT teams usually work in pairs....

With regard to small arms against vehicles, it's almost impossible to do anything beyond a minor damage result to even an unarmoured vehicle, even if the more solid parts of the vehicle are missed (the AV1 listing on each softskin).

For HE type rounds of virtually any size, it's worth remembering that even if the shot misses the target, fragments may still hit and do have a Pen listing. Even it the shot hits, the target should still be subjected to fragments, possibly multiple fragments which could conceivably do more damage than the initial hit (for a smaller size round against an unarmoured vehicle at least).