If I were going to write the rules I'd try and simplify the form so that anyone can enter anyway they want, but they may end up scored in a "simpler" category based on minimum mandates. Then I'd form it up this way:
Overall - (Everyone gets this one right?)
Aged based\Safety breakout:
Buckaroo(ette) - Mandatory (all competitors under 14 must shoot this category)
Junior - Mandatory (14-16)
Elder Statesman/Grande Dame (recomended)
Cattle Baron/Baroness ( strongly recommended)
El Patron/La Patrona (possibly required)
Tenderfoot (First timers only and should be asked to wear a yellow kerchief, and be partnered with an experienced RO that they shadow for duties, etc.)
Gender break for those ladies that feel they want their own.
Modern (Unless someone has a better name for smokeless)
Soot Lords/Ladies (Frontier Cartridge if you must)..
Modern (Calling them squaw grippers is funny but not appropriate)
Duelist (Double as well but only if both categories have enough entries)
Then your age categories
If a match director feels the need for other categories to broaden the draw for the match, then so be it, but they could be listed separately. (It could be that Frontiersmen really still want to be separate from Duelist Soot Lords despite really shooting the same way...)