Are you serious? I start a PBEM game, agree on a turn a day after turn 1 I load the game in the editor and have all the time in the world to do a map recon and test where I am the most vulnerable. Your weapon is your PC
Yes I was serious. A good map recon to find key terrain, possible routes of attack, etc, is an important part of CM (not in editor, but during setup or preview if a QB).
Don't think that anyone replicates their planned setup in an editor and than game it out to test where they are most vulnerable. It won't tell you about the enemies plans anyway, so I doubt the value you will get out of it. Plus it seems rather tedious / not fun / not worth the effort.
It's a game for entertainment after all. And like
@Meat Grinder said, PBEMs are great fun!
Like you said before, the AI is limited and won't really give you a challenge if the AI is attacking. Defending against a human player is much more dynamic and fun.
Due to corona I've more time at home and play a lot more PBEMs since (although I did play before, but mainly just one or max two ongoing against longtime opponents). If I didn't have a lot of work on my mind I'd probably be playing another couple of battles.
If my PBEM basket wasn't quite full ATM, I'd offer you a battle where I attack and you can go in the editor and test your vulnerabilities all you like. However, I saw Meat Grinder offered you a battle already. I don't think he would really care if you load it in the editor all day long.
So my honest advice as you seem to be enjoying the games: try it out. Play a PBEM and have fun. It would be unfortunate if you miss out on some of the best parts of these games, because you assume some things about how looking at the editor will make it unfair or whatever.
PS Your brain is your weapon in CM! ;-)