Cab Curtain keeps cool

This is probably old news to most of the readers but here goes. We accidently discovered while traveling in the southwest that the privacy curtain between the cab and living space could be d****d over the top bunk, hanging down, would help keep the A/C cooler in the cab. So my wife sewed up a long curtain that reaches from ceiling to floor and I installed a long shower curtain rod so that the curtain hangs just in front of the cab over bunk. Two advantages, first that the cab stays cooler (or warmer in winter) and we don't get the greenhouse effect in the living spaces, second is that the living space looks neater as the curtain hides the things we have on the bunk. The curtain is a 2 piece deal with Velcro to keep it closed but is easy to open. We chose a fabric that matches the décor and lined it with off white (which is on the cab side). We are well pleased with this modification.