Cropping a heavily animated comp.

I make animations with several layers contacting keyframed/expressioned scale/position/rotation etc. This creates an issue when I want to crop in on part of the window.

My current method is to make a null object, parent everything to it (or if some things are already parented, parent the lowest of them) and change its position/scale as needed. So far this has been working perfectly well but I am wondering if there is another less crude method for this, I have no knowledge of the unified camera tool, is that where I should look or is it more for 3d?

PS: Putting the entire comp in a new comp and making the crops there is not desirable, I already have many comps within comps so doing this is very processor intensive and results in a loss of resolution (my original footage is 4k, I Shrink it to 1920*1080 to animate, so cropping in on the 1920 comp loses the 4k).

Any tips/input is appreciated!