Living at the fringe of civilization and only reading English put two serious brakes on my opportunities to access research material; fortunately the local university with the best library did, in the 19th Century, consider the needs of potential British and Canadian officers. I'm going to assume that the contemporary practices for the British Army is not totally out of line with continental practice. If I can get actual French or Prussian numbers I will use them in preferences.
This means I have been able to borrow "The Elements of Field Artillery" by Captain Henry Knollys of the Royal Artillery, published by William Blackwood and Sons in 1877.
Three batteries might be deployed on a frontage of as little as 114 yards (close intervals), or as much as 345 yards (full intervals).
A single battery in column of route is 208 yards long.
If we look at our stand front, the smallest on which a gun looks good is 2cm, while wider than 3cm will be out of place with other frontages. I want to use 2cm; it is very much in line for 2 batteries, probably acceptable for 3). At 4, we are really starting to push things in wheel-to-wheel. On the hand, it is a lot easier when the base stand frontage is the narrowest possible rather than the widest.
Lets do another calculation. The Prussians had about 600-700 guns at Sedan. If we divide that into stands of 24 guns with 2cm front, that gives a total of 25-30 stands, with a total front of roughly 20-24". Given the importance of the Prussian guns, I do not see that as a problem in terms of how it will look on the table.
The stand depth will be 3cm - assuming 600 m for three batteries, that will meant we need to fit the limber in 3cm. That is optimistic for most 10mm models. I like limbers; if we can fit them in a 5cm deep base, that would give is a nice 800m (8cm) total for 4 batteries.
Knollys also states quite flatly that the longest possible range (given the limitation in human eyesight) is 3000 yards. However, he also cites a Special Committee of Rifled Field-Artillery, which suggests 4000 if the ground is at all open, with villages unsafe at longer ranges. The first British rangefinder is still "about to be introduced" in 1877.
He also says that under 800m the gunners are too close because of the risk of rifle fire on the gunners.