Welcome back! I'm familiar with your situation... I hope you're able to get some sleep.
If you're interested, you might start with my "best of MAME" xml (check my sig). That'll get you most of the way there, you'll just need to layer in trackball and lightgun games. I do the same thing, where I only keep the ROMs I want in my setup (though I keep the full set off to the side). I've switched to non-merged, which makes this a LOT easier since you don't need to keep parents + clones. Something to think about.