not sure 100% correct cos cant try it now but-
open the configuration setting file file 'user' in steamapps\common\Redorchestra\system
right up the top under default play is the name - if you can't enter a longer name here without the end letters being knocked off in game then i have no idea
tbh i suspect this wont work as i remember trying something like this ages ago on a game with same engine - oh and sorry if you have tried this already.