I have no idea how to mod, but I think I have the beginnings of a cool civ design.
Texas design for aoe3
CIV BONUSES
Gets (and ships) shipments twice as fast as other civilizations—this will let you ship many unit shipments, but upgrade type cards (eco and military) will cost 2 shipments to balance things out.
Your settlers will cost 130 food, they don’t gather extra fast. But they are hardy with extra Hp and resists.
Both of these together mean you’ll rely heavily on shipments to boost your military and eco, with a bad eco to compensate.
(The idea behind this was Texas relied heavily on volunteers)
ROSTER, age 2.
TEXIAN MILITIA, infantry, gunpowder infantry:
70 food, 10 coin.
120 Hp, 15% hr, 4.25 speed, 24 LOS.
20 ranged attack, 12 range, no multipliers.
15 hand attack, no multipliers.
5 siege.
The point of this unit is to be all around okay, without being able to really counter anything or Really do much damage. But don’t worry, you’ll be able to supplement these pitiful units with volunteers (not the unit) from your shipments.
TEXAS RANGER, cavalry, light ranged cavalry:
100 food, 80 coin.
180 Hp, 7.5 speed, 30% rr, 30 LOS.
25 ranged attack, 12 range, 2x vs heavy cavalry, 3x vs mercenaries and Native units.
15 hand attack, multipliers same as ranged attack.
8 siege damage.
This unit is basically a Dragoon that’s worse vs heavy cav, but better vs ranged units and mercenaries. It is also a good scout due to its higher speed and LOS.
Gains 2 range in the industrial age, and the imperial age.
RANCHEROS, heavy cavalry, heavy ranged cavalry, hand cavalry:
140food, 20 coin.
300 hp, 6.76 speed, 10% rr, 15 LOS.
28 ranged attack, 12 range, 2x vs light ranged infantry.
25 hand attack, no multipliers.
18 siege damage.
This is their anti skrim unit, they don’t have a proper hand cavalry.
ROSTER, age 3.
REGULARS:
Same as the United States Regulars, but you just can’t get them till age 3.
ROSTER, age 4.
DRAGOONS:
Just dragoons.
TEXAS MOUNTED MARINES, cavalry, heavy ranged cavalry:
630 hp, 6.75 speed, 20% rr, 15 LOS.
70 ranged attack, 12 range, 3x vs artillery and siege units.
70 anti ship ranged attack, 20 range, 4x vs ships.
30 hand attack, same multipliers as ranged attack.
80 siege damage.
Yes, mounted Texas marines were a thing (just for a short time), this is basically the US marine, but 2 pop and mounted.