The Martin logos are available online for download so you can have your local screen printers do the limbs for you. Or there's a company on AT that does it. They're called Onestringers and I believe Battledrum does it also.
Was going to say the same thing. The logos are provide for creative projects, another cool thing about the company. That is where I got mine for the videos. I think as long as you aren't mass producing things and trying to make a profit off of them, it should be cool. Typically if I am going to do something similar, I will at least make it known first, just so the "owner" is aware or has in some way giving permission first. I think in this case you should be good to go, to have a decal or a silkscreen done.