The recent improvements in engineering that HD has made with "Engine Idle Temperature Management System" (ETIMS it is also called) should help on your 2009 but some might debate how good it might be. In theory it should help. In reality who knows. As far as more info on ETIMS, you can do a forum search as a good deal of information has been written about it here on HD Talking.
I live in the Phoenix, AZ area so we can get pretty hot as well. I ride to work as well, all year round. I don't have a car that I can call my own. I could own a car but I choose not to waste my money on a vechicle that would sit around not being used.
My bikes over the years have never had oil coolers on them. I am faced with a bit of slow moving traffic but not to the extent that I read you have everyday. You mention "then about 4 miles on a freeway at about 5 mph or less". If that were me, I might do a bit of revving the engine when sitting in that slow of traffic so that the oil pressure were maintained (higher than idle pressure) to allow the oil to cool the engine. Revving would help but moving faster than 5 mph would also and that is your problem. Problem with revving is the cagers think you are trying to be cool by making noise and that is not the case in prolonged stop and go traffic.
The other problem with revving is it will cancel the ETIMS.
I LIVE IN THE HOUSTON AREA AND YEAH SOMEBODY TURNED THE HEATER ON. WHEN I'M IN THE TRAFFIC I HAVE THE ETIMS ON BUT I'M NOT SURE IF IT WORKS. HAS ANY ONE EXPERIENCED THE SYSTEM ACTUALLY WORKING.