Several pro-gun guys and I used to do 7-12 day trips in various parts of the country (before I got really busy!) and moving through states that allowed carry was a big deal when picking routes. In fact, I remember the big show we put on just outside the gate of Yellowstone breaking our guns down (on the way in) and putting them back together (on the way out) because of the old National Park rules....
Generally, I would compromise down to a smaller pistol when on the MC unless open carry was a viable option (legally and practically). A Tomcat 32 or Glock subcompact in the chest pocket (with holster) of a heavy leather jacket was common. I also used off-body carry with full size guns in a magnetic pack that rested on the tank of my bike somewhat frequently. For open carry, cross-draw made more sense than anything else....
-RJP