I too have a 40 watt panel .. mines inside the car on top of the folded back seat, not the most efficient place but anything it does is free to my MPG.
I have the plan to put it on the roof and raise the roof around it via coroplast like this
http://ecomodder.com/forum/showthrea...tml#post314105
Only building it directly into either the kamback or future boatail.