A rib-o-later is nothing more than 4 trays mounted on a rotissere bar that go round and round. I adapted a rib-o-later to my GOSM. Works fine, requires some attention because the trays have to be perfectly mounted so they don't rub against each other as they rotate. Practice, practice. Plus, now I've got a roissere for that piece of meat that benefits from smoking while being rotated.
By the way, on the needle valve, before you do that: See if your GOSM will let you do this trick: Turn on the fuel and on High on the GOSM. Make sure everything is working fine, then slowly move the GOSM temp control from HIGH towards OFF. Does the flame decrease or just pops off? If it decrease's, you've accomplished the same thing a needle valve does.
BE ADVISED that this not standard practice or intended use of the GOSM temp control so as a consequence, any action you take, you take at your own risk.