So: As far as is practical ~ The Division Base, Artillery stay close together, protected, near the SEP but within the Division perimeter (and may need to displace away from the SEP if the planned perimeter won't encompass the SEP to the end... this displacement better done once, near the middle or earlier, rather than continually and late.
The supply route(s) to the Regt Bases should be kept as simple, straight and clear as feasible, though routes protected from observation are less important (few (big) runs made in hours of darkness).
The Regt bases need to have covered lines of approach to the line HQ and Coys, as these will be drawing supply frequently and 'as needed' once heavy fighting is engaged. Artillery can be used to disrupt enemies who can see the supply route (or a temporary withdrawal of depleted Companies to a covered location, with replacement by fresh reserves ~ best done at night). The OOS unit can then resume reserve posture, resupply without risk of losses and rest. Each Bn and Regt should as far as possible be retained in one place (not so much to concentrate firepower/effectiveness, though this can help), but also to minimise 'cross' movements of supply, which as far as possible should enter units from their direct rear and from cover.
Consider dropping supply priority for exposed elements who are heavily engaged ~ they will then need replacement once their mission is complete, but replenishment will be faster if they can rapidly be brought out of the line and back to the reserve location, and protect the supply capacity. Shortest possible supply routes (consistent with the Base being out of direct sight) is good for turn-around times on emergency supply too. When we had the infantry A/T not being re-stocked (which I think is now dead and gone), I was seeing completed supply turn-arounds of basics and SAA at one hour intervals. This matters a *bit* less for artillery, as it takes a lot longer to unload the larger convoys and travel time isn't the biggest problem, but equally you have more trucks tied up, for more time overall.