I have a friend the same height as you who had this problem with his Concours. It is an oven especially when riding through traffic on a hot day.
He installed some highway pegs which attached through holes drilled in the fairing. He picked up a set of stock footpegs at a junkyard so it all matched ( the stock footpegs from the dealer were some mind-boggling price!)
He did it primarily because he suffered from "runner's knee" and needed to stretch out on long rides. The heat problem was a secondary benefit. He has a similar modification on his R100RT with Harley footpegs attached to the heads of the beemer.
Necessity being the mother of invention you know............
Get yourself some hot pads from the kitchen department and sew up a pair of chaps from them. Not only will they protect your legs from the heat, but they will also attract lots of comments as you go down the road with your tomato and celery themed clothing.
I'm rather tall as well, and when I tested the ZZ-R1200 last summer, I noticed this happening on both it and on the Honda CBR1100XX. In fact, I thought the XX had more of a tendency to bake my calves to a delicious golden color than the ZZ (perhaps because the XX made more power on the MO dyno?), especially in LA summer traffic. But either one of them was bearable in this regard, especially when they are being used as they were intended to- on triple digit cross-country trips. It seems weird to have your legs so toasty, but you'll get used to it. The ZZ-R is an excellent bike and I wouldn't think of this detail as a detraction from the entire package.