Oh wait scratch what I said above. I forgot I have "Arcade Hacks" as an actual platform in Launchbox, so since rocketlauncher is using that plugin, it's in the system list, and I set that emulator to be HBMAME in rocketlauncher. In RL i have the regular mame as an alternate emulator for DKII. HBMAME is the default emulator for my "Arcade Hacks" system, and i am pointing it to both rom directories, so it can load from either one. But most hacks will come from the HBMAME directory. The other crazy amount of hacks didn't really interest me when I saw what games they were. But then again it's hard to know just what was changed, they might be fun.
My HBMAME folder is only 30 gigs too btw.