regarding the rain noise. have you thought about spraying or rolling a liner material on the outside of the roof? it would deaden the sound and keep your roof a little cooler, and protect it a little better when you are throwing stuff on there. gluing your foam to the roof will help kill some of the rain vibes as well.
regarding the cooling fan solution. in the pop up section it is common to see a vent with a fan in it installed. i will see if i can get a link for you.
I only really use 5.7 feet of my truck bed the rest is empty i fill it with fire wood and the spair tire.Subscribed to this thread... I have a 96 dodge ram 1500 (ya gas 5.9, but couldn't afford the diesel),,, lots of great ideas here, I would love a contractors top, but have ext cab shortbox version,,