I use a "Bounding Box" macro to get the overall dimensions of the assemblies. This generates a 3D sketch.
Only in MEPs I would like to display only this sketch and not the others. I can have fun hiding all the other sketches that appear but it takes a lot of time.
Why not hide everything by default and only display this one by hand! (in the assembly, in display you have to uncheck sketches and they will be hidden in the drawing. In the drawing, you have to find the 3D sketch in the construction tree and show it :)
Or, in your MEP, you select a sketch segment, you press Ctrl+A to select all the sketches, you deselect the sketch you intend to keep by hand and you hide the others.
Otherwise if you see all the sketches of your assembly, you right click on the one you are interested in and you "reverse the selection" then right click and hide!