I just wanted to get some guidance before getting too far into the process.  I'm designing a custom plastic enclosure, with a few cutouts for connectors, etc.  The approach that makes sense to me is:

• Design the entire part as a solid block till happy with the look and size
• Choose my parting line
• Split the part in to two halves
• Shell each half appropriately
• Add internal ribs, bosses, and tongue/groove on mating edges
• Add any required cutouts
• Add appropriate draft

What I'm not sure of is the easiest way after I split the part into two halves to keep them matching in case of any changes.

It seems I have 3 potential options:

1. Split parts, continue working in a single .sldprt file with multiple bodies
2. Split parts, work on each half in its own .sldprt file
3. Split parts, insert both components into an assembly, then make edits to the parts within the assembly.

Are any of the above methods preferential over others?  I'm sure there's more than one way to skin this cat, but is my approach a solid approach?

Thanks for any advice.