I really doubt you can actively fill up those ids, there is probably a bug in warfare with the respawners. Base game does not have unrestricted spawning, every smart has a respawner and tracks which are still alive, and can only respawn the squad when they are dead.
It's not as easy as just changing the data type. It would also need done for SDK (which doesn't build on modern compilers) and all the level spawns would need recreated on this new SDK. Then there is the networking you would have to deal with, already it's limited how much data can be sent and how many objects can save, even for local network, which is basically singleplayer. As singleplayer the game acts as client and server at same time and ridiculously sends client packets. It's why saving is so volatile.
"I have a dream that one day this community will rise up and live out the true meaning of its creed: "We hold these truths to be self-evident; that all mods are created equal."