Snapping shapes to horizontal plane in perspective grid?

Hi!

I'm trying to create a "shadow" by using the perspective grid to lay a copy of text down on the horizontal grid behind text on the right grid. To show you what I mean, I've been able to achieve this on the horizontal/left grids:

The pink text is the "shadow". I want to move the black text to the right grid (which I have no trouble doing) and then I would like to move the pink text to the horizontal grid lines that run from the bottom left corner to the right edge of the image above.

I've tried everything I can think of and I don't seem to be Googling the correct phrases to find an answer.

So, is this possible? And if yes, can you please tell me how? Thanks so much in advance.