Don't get caught in the optimization trap.
If you're sending 7 unneeded bytes for 12 vars 15 times per second to 12 clients, you get unneeded 14 kbps. Is that really too much? And, if you update 5 times per second, which is enough for me, you get 4,5kbps...
My advice is, first, make your mechanics and features. Think about the optimization after that.

My laptop uploads with 5 to 15 mbps to my country and at least 256kbps worldwide (Its usually in the 512kbps-2mbps range)...