The general consensus is that being "on a motorcycle" qualifies as being "in a vehicle." However, I know of no case law on the subject. We won't know how the courts will interpret the preposition for certain until there has been an arrest and a test case. Care to volunteer?
Bottom line: Have your Concealed Handgun License to carry while riding a motorcycle and work to correct the law so that carry in a vehicle no longer requires a license any more than being in your home or walking about the public thoroughfares would.