JJM, I have not done the fan mod yet. I got the idea from wozwasnt and his "tiger internal mods" post currently on pg 3. Woz has some good photos of his dual fan mod. I'm pretty sure you could wire the fans to the motor terminals so that they would run when ever the tank is in motion. However, the fans would run forward and backward (unless you used a couple of diodes). The fans would still cool things down regardless of the direction of airflow IMO.
I tried out some paintballs today and found that the gun will break the balls on a sheet of plywood from at least 5 ft. These were "ExtremeSpots" brand that are NOT designed for the AEGs as found on HL and other RC tanks. I'm told that "Flying Color" brand now makes 6mm paintbals that ARE designed for AEGs. The paintballs that I used measure out at about .228" compared to .234" for the HL supplied orange bbs. Accuracy is not very good with these paintballs and they seem to break best at about 70+ deg. temps (two out of three balls broke with very good "splatter"). Will post more test results later.