I have this idea, probably will stay that way, but just thought I would explain it. Some of us build a HUGE battlefield map, I don't mean some half-assed DM map, but something more realistic. Afterward, we plan a gargantuan battle to take place there, and get 100+ people to play... So, yeah, I understand that this is probably a stupid idea and wont work, but I still thought I would explain it.
I hope you dont mean this huge... Light maps wont work at that scale unless they are VERY low detail.