As usual I go a slightly different way.
On tour I use the Bohn Armor pants as ?long john? type armored and evaporative layer under faded blue or gray jeans as the sun-reflective outer layer. Yeah, there are ?jockey? shorts of anti-microbial, quick dry stuff too, just to save washings of the Bohn. On top I wear the quick-dry (not cotton) tee shirt type evaporative layer against skin, then 100% of the riding time an armored mesh (all mesh) jacket.
When riding Death Valley or Big Bend type places a cut-off sweatshirt of old style cotton gets soaked with water, like my helmet and jeans do, but a lighter weight layer of a safari jacket, military type shirt-jac, or my vented outer jacket goes on top of the armored mesh layer. This slows the evap cooling to last about 3 hours or so. Nothing helps of course if you?re stopped in traffic in that heat, but you sure feel the difference when rolling again.
One of those cooling vests designed for the purpose works the same as the cut-off sweatshirt, but the sweatshirt material rolls up smaller when not in use.
When the temps drop or bad ju-ju cometh, the more typical outer layers, overpants and overjacket without the armor (I?ve already got that below) get unrolled and added to the jeans and mesh jacket layers. Without the armor it rolls up smaller/tighter. If it get really ugly I put the Gerbing heated gear (or whatever) against the tee shirt layer, and add the quilted liner to the outer pants (again, I?m armored by Bohn as bottom layer) .
Now, when going in a restaurant, museum, or to get that Nat?l Park stamp, I can choose to peel the outer layers, roll them small (no armor) and cable lock them to the seat like Charlie B talked about, and go in with only the mesh jacket (it has my wallet) and jeans. For fancy places I can put the wallet in my jeans, cable the mesh jacket too, and slide on the safari jacket to look almost like I?m house-broken.:redface:
I know it?s not the way most folks go, but it?s worked for me for the last 300K miles in USA and Europe. (OBTW: I never get guided tours. I just figure it out on my days off, thanks.) You can see my testimonial to Bohn at actionstations.com, if you?d like and if it?s still there. It?s five or six years old now, but there's not a word of a lie in it.