Masking armored vehicle infrared signiture (from above)?

[BraselC5048]

I've got a "massive conventional warfare between TL 8+ major powers" setting, and one thing I'm wondering about is the practicality of (mostly) reducing the infrared visibility of a tank, at least from above. Mainly to help hide the tank from hostile aircraft and helicopters., so infrared signatures from the side are far less of a problem. The first obvious possibility is to have the exhaust from the engine (the main heat source) directed downwards or downwards and to the side or rear, instead of out the top. Air intakes for the engine (likely gas or diesel, possibility gas turbine) would be from above but on the sides, with a 90 degree turn to get to the engine compartment. Finally, the main signature would be reduced by a layer of insulation over the engine compartment. And possibly a poor-heat-conducting layer of composite as or above the top armor.

Mostly I'm wondering about the practicality of it, and how effective it would be at avoiding easy aerial IR detection, and at best reducing the hit rate of IR-guided (air launched) weapons. From ground level, simply visually seeing a big old tank wouldn't be any harder then IR detection.