Obviously the "WHO" part is decided through internal politics typical of American political party operators.
Once you start up you do your next round of committee selections differently. Since one objective here is to prevent a small regional party (which is what the GOP-e is) from taking over the total organization for the purpose of running their own insiders, rules will need to be written for initial implementation before the first invitation to any state party is made.
A more formal coalition member standard (meaning additional caucuses) will need to be prepared. We have had quite enough of people with only the most tenuous connection to Republican party principles sneaking around and distorting the message. That, btw, is a common problem with large semi-voluntary organizations ~ the existence of phonies who represent themselves as spokesmen for the group.
If I understand you correctly, you want the states to change the makeup of the RNC.
Can’t they do that now since they control who is on it and those then control who holds the RNC offices?