Trim a single packed sprite?

Hey all,

I have a game I am making that is an endless vertical climb game. The player has two colors his character can be(Taps the screen to switch colors); depending on which color he is he can climb upwards on the background or climb upwards on the obstacles. Some of these obstacles are as wide/tall as the screen so many of them fill up their own atlas. Majority of these obstacle assets take up their own 2048by2048 sprite sheet. Which I'm fine with b/c I'm doing heavy resource management to begin with.

My problem is that I have no way to trim these sprites in unity. Everything needs to be a POT(for compression reasons, ios mainly) which leaves me at 1024 or 2048 texture sizes so as you may expect there is tons of transparency space. But when I do something like sprite.position = Screen.Height + sprite.bounds.x I'm given 2048 for the height when the actual height might be anything from 1025 - 2048. I can set the border manually for each sprite in the Sprite Editor window but when testing the sprites size is still 2048by2048 in the scene.

I see a trim button in the Sprite Editor window but much to my great dismay that is only available to multiple packed sprites. All of my sprites are individual assets and cannot be set to multiple. So how can I trim the transparency from a single sprite? OR How can I get the actual height/width of a single sprite??

Thank you for the help.