Did the ring with two of my mates yesterday, on my GS though. No way would I attempt it in a day on my Duke!
Plus make sure it will be open when you get there we had to wait till 545pm for the public session, weather was great 21 euros for one lap goes too quickly for my money but hey I ticked the box
Stayed in Valkenburg the night before and watched the footie great bikers hotel check it out highly recommended
Linky here about 2hrs from the circuit through the Effel National park brill roads to get to the Ring.