I served in the Army in Okinawa from Jan 1970 to April 71. I have a service connected disability obtained on a firing range. Though I did not set foot in Vietnam, am I still qualified for any Vietnam Veterans benefits such as license plate, etc. I was close to a lot of people who were in combat and supported the conflict for personal reasons.
I'm not at all sure what benefits you think there are that the Vietnam veteran receives that you don't? License plates are a state by state system of different plates and each state will have their own requirements for costs and such. Free license plates for vets are based on the vets disability, not where they served so if you aren't 100% rated, I don't know of any way to those benefits. Otherwise, I can't think of any benefits you don't already have access to.