Design as a separate product exists because building without one costs more than both. The deliverable states not just what to build but why — so future changes are decisions, not archaeology.
Distance does not change the model. For remote and regional sites we often do the design and configuration ourselves, then have a local installer handle the physical work — racking, mounting and cabling to our drawings, with equipment that arrives already configured. The site gets the same engineering as a metro build without flying anyone out for work a good local contractor can do, and the installer is never left guessing at intent.
The same goes for changes over the life of the network. A remote site never needs to wait for us to come onsite: we design and configure the change, and local hands fit it. It is worth a conversation before new equipment goes in, though — we have seen a well-meant local addition conflict with the design it joined, where a quick call first would have produced something better that worked with what was already there.