Oh... 20 something years ago I worked in Aramco which used the "Universal Plumbing Code" (universal my a**e) and chlorinated pvc pipe 
I had to "remake" your image a little for a CPVC layer, did not bother about the others and it depends what you want to align.
First, the align tool options is a bit wide, you need to widen the left side to show the extents options.
If Align ... Relative to ..... Image is set then you do get those corner indicators.
However that setup does (1) center horizontally and then (2) vertically.
For three little layers like that, not align tool which is awful, I would be inclined to put in a guide (s) and move manually.
I had to "remake" your image a little for a CPVC layer, did not bother about the others and it depends what you want to align.
First, the align tool options is a bit wide, you need to widen the left side to show the extents options.
If Align ... Relative to ..... Image is set then you do get those corner indicators.
However that setup does (1) center horizontally and then (2) vertically.
For three little layers like that, not align tool which is awful, I would be inclined to put in a guide (s) and move manually.