A former colleague of mine used a master sketch (drawn in a part file) to create outlines for multi-body parts, dimension all the vitals etc, but not actually create any bodies (or surfaces). He would then insert the master sketch part file into a new part file at the top of the tree, converted whatever lines he needed, then created the part. Then in this latest part file he could add any extra features that didn’t have any thing referencing them, e.g. an extrude cut here or there, fillets, chamfers etc. Once all bodies were created, he’d insert the master sketch part file into an assembly and mate all the subsequently created parts off that (which saved on loading time since it is lots of smaller parts rather than one large one). Any dimensional changes, additional parts needed etc could be easily updated or added to the master sketch and would update across all parts.
This method is a bit of a cross between multi-body part modeling and modeling within an assembly.
And is of course much easier when using basic geometries - we all know converted splines likes to make life difficult.