kinda sounds like your leaning towards mixing the masters in with "normal" stock. for me, not interested and wouldn't attend nationals or for that fact even race regionals.
would it make sense to just mix mod/19t/stock 1/12 scale altogether and then give out awards based on finishing within the group.... i mean you might as well cause some with 19's would be able to beat some with mods.
why not just up the number of racers required to make a class at nats. less then 25, no class.