My reference is experience. The additional heat I am referring to, is not normal heat coming from brakes, hubs, etc. but heat from the tire rubbing on the side of the shock, if they do flex enough to actually rub.
McPherson strut cars already have more heat into the shocks than conventional suspension cars, as the shock bodies are actually a part of the hub/mounting assembly. Coventional shocks get heat only through a very small connection point and through the surrounding hot air in an enclosed wheel well.
Adding the friction of a tire rubbing against the shock on a regular basis (laps) is additional heat they do not need.
That was my concern and just something for the original postor to consider with his 2mm clearance.
I understood your question in a nice way and respond accordingly
