I plan to start using the new Sharp Practice 2 rules from Too Fat Lardies with my 15mm ACW collection, which I am sure will provoke cries of horror from those who consider them to be a "28mm ruleset". This obsession which some gamers have with a supposedly correct scale of figures for a set of rules is something I find hard to understand and I am not alone in this. The distinction is more between using individually and stand based systems, though I can appreciate that it makes sense that the figure scale is greater than the ground scale as Mike Whitaker explains.
Getting back on topic I find that my preferred range of miniatures for 15mm ACW, which is Peter Pig has a limited set of the figures I might need for support options in their range, but Freikorps 15 now sold by Total System Scenic does have a lot of the things like a US Army mule cart and Engineer figures for the ACW in their ranges. Though if you go looking the mule cart is under the US Mexican War (which of course it can be used for too).
Initally I may well start playing using multiple bases for the line troops in my Union and Confederate forces with just the leaders and skirmishers on single bases, but as I paint up more from the lead pile I will probably build up to being able to field most of the infantry in a game as singly based. The cavalry will probably still tend to be on the 2 figure bases I already have and likewise artillery bases will be my current ones with the crew all fixed on meaning I will use markers to show casualties.
The Friekorps range also contains plenty of other vehicles that would be useful for the different supply options for SP2 in 15mm for periods like Napoleonic or 18th Century European wars and 15mm means that it will be possible to substitute cm for inches on the measurements and play on a smaller area if space is an issue and it will feel less of a mismatch than using cm measurements with larger scale figures.
Now just have to get back to terrain making, painting and waiting for the rules on the 23 April.