Most spots are either unsafe because you can be seen, or unsafe because they're too far away from the battle scene and people would notice you're not there.
After a lot of testing, I found this to be the best hiding spot
It's a hut at the right side of the horde base. Go inside, get behind the column, and /lay or /sit. The column itself will block the sight from the people around.
Remember to disable your PVP ranks to make your name smaller and harder to see.
Stealth if you can. Use orb of deception if you're a tauren.
Hope it helps.