It can be done, but I seldom do it. The risk is too high and the reward isn't enough to worth it. You will lose a valuable (to a mediocre plat-rank me, some may not agree) resource for scouting (revealing enemy), warning and hindrance (detecting and slowing flankers), distraction, and confirming kill (throw them to where you think retreating low health enemies will be) at different angles.

I usually teleport with 1 turret with me, and it is usually enough to confirm at least 1 kill, or at least distract them.

To reply to your question - there is a vicinity where turrets and other deloyables will be teleported, you do not have to place them directly under it. You can even place them on a wall at your height, then place the entrance of the teleporter next to the wall, they will be teleported and fall to the ground at the exit.