score:1
Self answer as more information has surfaced recently and I now have his full travel itinerary.
In 1834 my ancestor, who had eventually settled in The Netherlands, had a large farmhouse/estate build. My family still owns this house today and it is currently occupied by my aunt. In April 2021 we embarked on renovating the attic space to convert the attic from storage-area to a master-suite bedroom and add much needed roof insulation as well.
We knew that the gable-end wooden wall on one side was actually a false wall, behind which would be a very rickety old chimney.
So we took down that wall to remove that chimney altogether and gain an extra meter of floor-space.
As we took the wall down we discovered that the chimney was flanked on both sides by a build-in cupboard.
In one of those cupboards we found a large (woodworm riddled) travel-trunk containing a bunch of notebooks and assorted papers.
While most of the loose papers in the chest disintegrated into dust as soon as we touched them the notebooks turned out the be more sturdy.
We found they had been so-called day-books maintained by my ancestor and later his son.
Day-books are similar to diaries. They typically give account of important events (travel, new job, births/weddings/funerals in the family) in the life of the writer, but (unlike many diaries) they mainly stick to facts and add little personal information about the writer.
It took a while to decipher his handwriting but I managed to distill the following from the day-book entries in May 1805:
From other reasearch I have established that on the Koblenz to Bastonge leg layovers at Clervaux, Prüm (halfway between Nürburg and Clervaux) or Nürburg were all possible.
From the undated entry for Clervaux I presume they stayed there for 1 day.
The layover at Bastonge was 1 day (else the dates wouldn't match up), but could have been 2 if there was no layover at all on the section from Koblenz to Bastogne.