I think they might be best kept separate, to be honest, as the “visit” feature wouldn’t help with the stock reduction part, which keeping these as orders/invoices does solve. Invoicing Sequence Numbers is also related here as that would prevent these from interfering with the numbering sequence of their own orders/invoices.
In this case, I’m not sure that a straight “don’t sync £0 invoices to Xero” is the right solution as it’s quite heavy-handed and you might have a genuine £0 invoice of your own, which should be synced (for customer statements, etc). However, if we built Invoicing Sequence Numbers and allowed different customers to fall into different sequences, such as one for 3PL customers and one for all other customers, then we could add an option to disable the sync of individual sequences to Xero completely. If we went down that route, this would also then not need the Include a "visit" on a (delivery) run/route changes at all (but don’t worry, we’re certainly going to build that feature regardless)!
Super-requests (great term btw!) are a double-edged sword - on the one hand, they can get lots of votes and get to the top of the list, but they can also become so big that the implementation is hard to organise and test. Often it can be faster and easier for us to build, test and release smaller components of big features in stages, and by getting there in smaller steps, we actually get to the end result faster.