Had the "Nite" system on my previous truck which was a volvo. It was a piece of junk. I was lucky to get 7 hours of A/C with brand new batteries. Also, if it was about 80 outside you could forget about it. It would never keep it cool. I would not recommend anyone spending money on that system.
I have friends that have the "clima-cab" system. They say it works great but they had to remove their top bunk for installation.