Yup, good idea. At least an edge will get you lined up but we all know, as soon as you choose "that" edge, next revision, it's the first one that is changed.
The tricky part about a datum as a reference is that this is a reference to a point. When you pick on an edge, you're getting one vertex or another or 0.84742 along the edge or the like. If the datum happens to be in the right orientation, it's fine, but it ends up askew (imagine on update, the orientation of the datum relative to the orientation of the view is such that the datum has been effectively rotated 5 degrees each along the screen X and Y axes, and is now not edge-on) it becomes problematic to say which point should be considered for the alignment instruction.
A datum *point* can be employed well enough (and is currently possible), but a datum plane not so much.
The Origin tab of the View Properties allows you to select the origin of the view, and among the selectable references, you can select Coordinate System, Axes and Points. It is thus possible to define the origin of the view 1 on a well-chosen Reference, and to do the same on the view 2. Thus, an alignment which you will leave on the option at the origin of the view (for the 2 views) will allow you the alignment "Coordinate on Coordinate" that you want.
