We understand that this provision is required in order to address the bill raised by the transporter. You have 2 provisions for this:
You can create Service Invoice Adhoc where no logistics gets tagged.
You can create a miscellaneous type LR (connecting to the managed site) and tag the same in Service invoice against document. Please find attached the screen shot for the same.
Given the workarounds available, we are marking this idea as "Unlikely to implement". In case we gather enough votes, we may reconsider this in future.
Keep posting your ideas!!