The normal heat kit for me on an ST1300 is smart wool socks, synthetic shorts, shorts, airmesh over pants while sitting on a bead rider. Last week I took off the bead rider and was surprised how much hotter it was. So in conclusion, the bead rider seems to be the way for me to stay the coolest below the waist, I will try it without the bead rider again with the normal kit, however I am pretty sure the bead rider is the reason everything else works...
Heat was a constant friend (*ahem*) on my ST1300 as well. My Gold Wing beats it in spades in that regard.
Funny you mention a Bead Rider. I bought one to try, but haven't done an A/B comparison yet. Part of me looks at it and thinks that I'm going to start driving a cab in NYC, but the other part of me says "Those cabbies may know something that you don't."
I'm banking on my Joe Rocket Survivor jumpsuit for hot weather, I like how it opens up a wide mesh stripe for ventilation and lets air flow between lower and upper with no encumberance of a belt. I'm wearing an XXL, since the XL was too short for me, want to buy the XL? It still has the tags, all I did was try it on.