I moved to MA in 1992, and registered my 1985 Mitsubishi Starion and got a green plate. I later traded that in for a VW Corrado, and transferred the plate. Later, I bought a BMW 325i and once again transferred the plate.
In 2000, I bought a 1981 Delorean, ordered new plates for the BMW, and transferred the green plate to the Delorean. (Didn't want a front plate on that car). It was really simple. I think all you do is do a transfer and new registration for the existing car. I do think my insurance company (Liberty Mutual) helped me with the proper forms.
But also at one point, I had the Delorean and two other cars. I never ran those other cars with the front plates, and never got pulled over or a ticket for no front plate. YMMV!
I since moved to a different state that also requires front plates, but I don't run with them either. I was sad to loose the MA Green plate on the Delorean. I'm willing to accept the cost of the ticket(s) (if I ever get one) as a "cost of doing business" in exchange for not ruining the front look of these cars, especially the Model S.
But transferring the Green plate to a new or other car is relatively easy. I think MA even allows you to transfer the green plate to a family member.