I’m also (but very, very slowly!) building a mid-C18th town/port.
For urban life (including shop frontages) I looked at the work of Hogarth.
His Gin Lane is quite a busy London street scene and if you're not familiar with it there's an image at Wikipedia
here. He shows the shops as having an inscription above the door (I think of proprietor and product/service) with the real advertisement being from a sign of the protruding/hanging type.... in this case in the 3D style: the three balls of the pawnbroker, the coffin of the undertaker, the jug of the tavern.
In some of his other works, many of the shops do have large elaborate art work for signs but as far as I recall they are also protruding from the premises rather than being fixed across the front. Examples can be seen in Election II: Canvassing For Votes (
here).
This is not to say that banners across the frontage weren’t used (for example where the front of the shop might have been seen across an open space), I just haven’t seen any shops presented in this way. After all, it is feasible that a merchant with harbour side premises who has wares to sell to sailors will have a banner facing out into the harbour. In this vein, the Stagecoach (
here) shows the tavern sign fixed flat to the wall.
Am looking forward to reading/seeing more of your project in due course.
