Here is a way to make a very simple carryover system to play skirmishes against the AI:
Consider your army divided in Infantry; Armour; Afv (trucks, armoured carriers...); support (artillery)
Choose the number of battles you will play in this campaign (for example 7) (you should consider a dynamic campaign, thus choosing 5 battles and... after the 5th roll 1d10, on 5 or less the campaign is over, if not play the 6th battle and reroll at the end..... on 6 or less the campaign is over.... and so on)
Roll 1d10 with some bonuses for infantry, armour, afv and support (you should choose the bonus considering the campaign you want to portrait, so for german barbarossa you might use +5 for infantry, +4 armour, +5 afv, +2 artillery) those are your army supply
Play a skirmish, if you win a very small you gain 1 point, a small2, a medium 3 a large 4 a very large 5; if you lose you will lose the same amount of points (so from 1 for very small to 5 for very large)
For every loss you suffer in the skirmish lose 1 supply for the given kind of supply (so if you lose 2 infantry and 1 armour, subtract 2 infantry and 1 armour) .... if a supply goes to zero you can't buy any unit of that kind in the next skirmish
At the end of the campaign just see how points you gained or lost, then you will have the outcome of the campaign:
1 very small victory ( or -1 very small defeat) ..... to 5 as a very large victory (or -5 very large defeat)
I use it and i enjoy this simple and very fast carryover .... hope you can have fun with this idea
