I have a description from a Danish scholar who visited in 1785 (Efterretninger om begge Sicilierne, samlede paa en Reise i disse Lande i Aarene 1785 og 1786 ved Frederik Münter/Information about both Sicilies, gathered on a trip to these lands in the years 1785 and 1786 by Frederik Münter, Part one, Copenhagen, 1788, pp. 94-111). It is in Danish, but I can provide a summary and some translations.

All the objects, except some of the murals, found at the site was transported to the Palace of Portici, belonging to the king of Naples and Sicily. Here was also stored and exhibited the objects found at Herculaneum. A special suite of rooms was reserved for the larger murals.

Every foreign visitor to the site of Pompeii had to hire a guide, and it was strictly forbidden for the visitor to write or draw anything. The reason for this was that the king was in the process of publishing a grandiose work in multiple folio volumes, entitled Le Antichità di Ercolano (8 folio volumes, published 1757-92) containing illustrations and plans of all the excavations and the king wanted a monopoly on this information, as well as further the sales of the highly expensive work. But our Danish author still managed to write down some inscriptions and even draw a ground plan of the House of the Surgeon, while the guides weren't looking (this is reproduced in his book). So the vigilance of the guides was obviously not perfect.

Münter also tells that there are few workmen working on excavating Pompeii, and that they are lazy and slow, and he estimates that with a workforce of a couple of hundred, the place could have been excavated in a matter of two years.

Still he is impressed with what has already been exposed and he can really sense the daily life of the Romans from these buildings "which one almost thinks was only recently abandonded" (p. 107). "One enters the houses, gazes at the rooms, tricliniums, the baths, the basements and everywhere the entire interior decoration of their living spaces. One can see temples, theatres, soldiers quarters, the city walls, the gates, graves outside the town on both sides of the road, and ends up seeing the villa of a wealthy man, which gives us a clear notion of the splendour of the villas of the ancients."

I assume this way of narrating the views at Pompeii follows somewhat the route that he was led on by the guides, first the town and the various buildings there, then out of the so-called Herculaneum Gate along the road to what is probably the Villa of the Mysteries. Münter is unfortunately not very detailed overall, because as he rightly claims, you could find descriptions of the various sites in a lot of readily available travel descriptions at the time.

Although he does mention that no ground plan of Pompeii had yet at that time been printed, but he expected it to appear in the mentioned folio work published by the King of Naples and Sicily. However numerous artists who had visited the site had drawn up plans afterwards, and often corroborated the results with fellow colleagues, so there did exist hand drawn "pirate" versions of the ground plan, but not readily available and definitely not official plans and guides sold to tourists. Tourists would have used travel accounts, as for example Voyage pittoresque ou Description des royaumes de Naples et de Sicile (1781-86) mentioned by Münter, so that was probably his "guidebook", where several views of Pompeii was to be found as engraved illustrations.

Note that this is how the situation was in 1785. It could very well have changed considerably the following decade as the political upheavals of the French Revolution entered Italy.

Further note: Frederik Münter (1761-1830) was not a wealthy man, he was a son of a clergyman, had a degree in theology and he travelled on a grant from the danish government in order to study theological manuscripts in the libraries of Italy. So his experiences was probably a bit different from that of a grand signeur of the aristocracy going on the Grand Tour. Perhaps a rich nobleman could use bribes to access where Münter could not. But he was a keen observer with an eye for details, so his account is definitely faithful with regards to the particulars about the guides, museums and so forth.