EDIT: Turns out that doesn't work since Brimstones are considered to be EOGRs by the game, and thus their associated rails are TLRs. Oops. Stock loadouts it is. :P
(Sorry for the double post, wouldn't let me edit the previous one)
Another workaround I was thinking of was simply redefining the Brimstone 3-pack as an ATR instead of a TLR. The only way I could see this causing a problem would be if Brimstones aren't considered to be a weapon type compatible with ATRs.
Huh, interesting. But wouldn't you have the issue of the missile having no guidance since the game is technically treating it as an unguided rocket? (Sorry if I missed something, I just got started messing around with mods for this a few days ago and still haven't worked my way through the nuts and bolts)
Ah, thanks. Next question, what if I want it to select the proper rack with a customized loadout, (i.e. one not defined in the loadout file of the aircraft but rather created in the loadout editor before a mission)?