A popular "sixth gear alternative" is to switch out the 15 tooth front [counter shaft] sprocket for a larger 16 tooth sprocket. This lowers your highway speed RPM's by about 300. Running a taller tire than factory stock, such as a 130/90-17 as apposed to a 130/80-17 will lower your RPM's a little, although I've never investigated how much.
This change to a 16 tooth sprocket has a few trade offs. You may find yourself working the clutch harder, and finding taking off from a dead stop on a fully loaded, two up bike something that might require developing a technique to pull off. I'd experiment a bit before I headed out on a journey with that sprocket combo. The stock gearing offers a pretty good compromise.
“many a trip continues long after movement in time and space have ceased”- Steinbeck, [I]"Travels with Charlie"
[FONT="Century Gothic"][I]Sometimes your only available transportation is a leap of faith[/I] [/FONT]