Re: How would you do it?

With Bit-X you can earn 0.36/month with one hero, for 300 posts. I think it is the highest possible payout right now.

With 5 accounts and 0.0012/post max is 4.32/month.

Not too far from 10 BTC/2 months, but you would need make 1500 posts/month

Hmmm a hero member making 300 constructive posts can earn 0.36 btc a month, so you can get only 1.8 btc a month with 5 hero accounts but not 4.32 btc. Plus you will need to spend many hours on bitcointalk every day to make that much of posts.

is this even legit? can you do 5 account for campaign, i think it's bannable

Usually campaigns do not allow participation of several alt accounts. Such accs could be banned.
So if you have 5 accounts you'd better use them in 5 different signature campaigns.