I'm still back and forth on this...if I eliminate the Home Guards, then the AI will have to build Home Guards to fill the holes, which means it will spend less time building other, more useful things. The AI will mostly likely want at least 2 units defending a city (especially under CSA government, to take advantage of additional military martial law effect).
Even if I took out say all backwater Home Guards of cities of size 1 in CSA and USA, that would only eliminate maybe 40 units or so. Out of probably 300+ to start the scenario...I don't think it'd make much difference.
What I WISH I could do, is set the units to FORTIFY right at the start, so players of the scenario wouldn't have to do it themselves for every Home Guard or Garrison.
What do you think about this: Make Home Guards a little weaker (say stats of 1/2/1 for regular Home Guards, and 1/1/1 for the Home Guard (small)), and give them a cost of 0 (or 10), but they still would require 1 population. Then, if the AI actually would still build a couple for defense, then I wouldn't need to place as many initially.