Since heat is an issue you should try a LightRail instead of just spreading the bulbs out. Since the light moves it not only distributes light to shaded leafs, but it also eliminates hot spots.
The moving track is a good idea! I used a stationary track with two lights and recently switched to a LightRail and my yields are so much better! Its better since the light moves and the light gets to more of the leaves and since your light would be moving hot spots are eliminated so you could...
i love my LightRail. the benefit - with moving your light you can get into the lower leaves with light. also, by moving your light it eliminates hot spots and that lets you run your lights closer which allows you to get a bigger bang for your watt. but man, im thinking 8 feet is too far to move...
i had a different problem dude, but just call them and they will fix it and get it back to you fast. i cant remember the # but their site is lightrail3.com.
what brand of light mover did you purchase? ive only used LightRail and i love it, if that is the brand you purchased then yes its really is all they brag to be. the reason you want to move your light is because then the light comes in at angles so more of the mid and lower leaves get light...