A different workflow

[FenixPheonix]

Our team uses layout sketches and in-reference parts to plan out a lot of our layout in Solidworks. We add holes in assembly mode and then propagate them to the parts, which helps to ensure consistency between the pieces. I'd also recommend investigating some of the specialized tools CAD programs have for this. For example, we use weldments sketches and extrusions to lay out our chassis even though it's not welded, allowing us to do the whole thing in one part rather than seven, change dimensions much more easily, and automatically generate cut-lists.