Due to lack of space and money I have done something close to heresy for some wargamers - one base represents the whole unit, not a number of bases representing the unit.
An infantry corp with support. Four infantry bases represent a brigade.
One base of infantry (three figures) represents a whole Battalion, a base of cavalry (two figures) represents a whole regiment and one gun and crew is a battery.
At the moment the majority of my figures are Eureka Miniatures, with some AB and CGM thrown in to fill the gaps in the Eureka range. I am also trying to get some Battle Honors British generals so that I can complete my command bases.
By painting some extra units I can swap out a few units to totally reconfigure my army to represent an different Corp.
For my Brigade command bases I am using Colonel figures with a standard. I know Brigades didn't have standards, but I wanted to add them as a bit of pomp and pageantry.
I had to make some changes to the rules to accommodate my thinking - counters are placed next to a unit to indicate formations, and I need to use a record sheet to record morale and casualties, but this works ok.
I still need to finish off my command, artillery and cavalry units, but I am able to field an army a lot cheaper than I could if I used the basing conventions in the Black Powder rule book, especially if I made my army in 28mm!
My Friend and I have played a number of Black Powder games, including this minimalistic approach and it works great. Being able to field a force larger than a brigade allows for tactics, defense in depth and even a reserve force is a vast improvement on Brigade level games, and we can field the armies in a smaller area.
For the cost involved it is also feasible to build a number of armies cheaply. I am contemplating making a Bavarian and a Russian army, and I think I will put together a French army so that I always have the forces at hand to play a game.