You can use Jass NewGen Pack.
Link:
http://www.thehelper.net/forums/showthread.php?t=73936
The only problem is that it's not quite compatible with the current version of Wc3. I suggest a dual install for wc3. One for playing and one for the Editor. I'm pretty sure it works perfectly with 1.21b. Using it, you can go surpass any editor limits, like map bounds and doodad limits and it has a lot of pretty cool features. Anyway, I'm not sure why you would want to make a huge map. It'll just make it harder to run. But still, I hope I helped.