It's not exactly a direct response to the question asked but it is perhaps worth noting that guns per 1,000 men is a commonly used measure of artillery strength in Napoleonic armies.
Most armies would have had, on the battlefield, between 1 and 4 guns per 1,000 men, with something around the 2 per 1,000 level being probably commonest.
So Wellie at Waterloo had 2.3 and Napoleon had 3.4 guns per 1,000 men. At Austerlitz Napoleon had 2.1 and the allies had 3.7. At Eylau Napoleon had 2.7 per 1,000, the Russians unusually had 6.
A French brigade was typically two regiments of two battalions totalling 2,000 to 2,500 effectives at campaign strength. A division was usually two such brigades so would therefore be 5,000 or so. At a typical French guns per 000 men ratio, there would therefore have been between 10 and 18 guns on the field per such 5,000-man division.
It is your call and your rules' to what extent if any you observe this sort of detail. Two French foot batteries, though, would have totalled 16 guns, so in your shoes I'd be looking to represent that many guns for a force of divisional strength.
A foot battery would have between ten and twenty metres between pieces so a footprint between 80 and 160 metres wide. For comparison a 600-man battalion in line three deep would have been 200 men wide and about 120 metres' frontage. So the frontage of a battery and of a battalion would have been about the same. You could probably fit two model guns into that space, I would say.
If it were me I would also model a parked limber and ammunition wagon and place them behind the unlimbered battery on the table, as this is what was done and it significantly congested the area in a deployed battery's rear.
