I seem to recall that with the use of gangs and other mini-multiplicative abilities, you could fairly easily field a force of 25-ish miniatures. Above that it gets tougher, or you start to warp the game too much.
That said, you can squeeze out a few more simply by having 12-point leagues instead of 10-point leagues, though IIRC Dave usually suggests the "more points" option very sparingly and usually to do things like add a vehicle to each side. I feel like 14-15 points per league is probably the most you could push the PA system without it seriously affecting the inherent game balance, and I almost certainly wouldn't try to run more than 12 points of actual characters/gangs (i.e. infantry).
Also, if you go above the 10-point limit I strongly suggest a larger gaming surface. PA is very adaptable to slightly larger areas like 3' x 4' or even 4' x 4' instead of the normal 3' x 3' without any major rules impact, and I would consider a small increase in size a must in conflicts involving numbers of figures well above the normal baseline. That goes double if you were looking for the feel of a military engagement (where there's some probing, scouting or skirmishing prior to a full engagement) rather than a brawl, and especially if each side is going to have one or more fighting vehicles.
All good suggestions.
I usually use Ally (level 2) characters for this sort of thing. Obviously, you'll get to have more figures if you make then Followers or Gangs, but here're some quick character profiles ---
Regular Soldier 1 (Ally) -- Marksman: Shoot: 3d6, Brawl 2d6, all others 1d6
Regular Soldier 2 (Ally) -- Marksman: Shoot 2d6, Brawl 2d6, Dodge 2d6, all others 1d6
Green Soldier 1 (Follower) -- Marksman: Shoot 2d6, all others 1d6
Green Soldier 2 (Follower) -- Fierce: Brawl 2d6, all others 1d6
Green Soldier 3 (Follower) -- Agile: Dodge 2d6, all others 1d6
Squad 1 (Gang: 5 models) -- Armed: Ignore multiple fights penalty when shooting.
Squad 2 (Gang: 5 models) -- Disciplined: Always counts as being in cover.
I hope this helps give you a few ideas. Have fun!
