A couple of us have been playing more and more BF2 and tried to figure out how to get larger maps and more people in single player and me and jeric finally got it today.
For 64 player maps in single player downlaod this mod
http://bf2sp64.googlepages.com/then to get 64 bots in single player
Open up the folder C:\Program Files (x86)\Steam\steamapps\common\battlefield 2\mods\BF2\AI
Open up the file AIdefault.ai
I copied the main part you need to look at
rem Example for 32 bot game with expert bots
(*) rem aiSettings.overrideMenuSettings 1
(*) rem aiSettings.setMaxNBots 64
(*) rem aiSettings.maxBotsIncludeHumans 0
(*) rem aiSettings.setBotSkill 1.0
To get more bots just remove just the REM in front of the ai settings here, i stared the ones you need to remove. You can change the number after setMaxNBots to whatever you want just dont go past 64 can cause the game to crash.
You will need to chane that file for any mod you have installed and want 64 player bots.