Bad idea to have mid-battle saves imho ... just adds a whole new level of needless complexity (if My guess is correct that it would be hard to code without a lot of new work)
Instead, why not a save pop-up ... or even an Auto-save ... after each Tactical Battle?
If an auto-save, it could be a single stored AutoSave for that specific purpose ... only for saving right after a battle ends, and once it saves a new position the old one is erased (it takes the place of).
In this way ... even though its a very specific (and non storing) autosave function ... you could fight 10 battles, and quit during the 11th, and it would save right after the 10th ...
so when you loaded the game, the 11th would initiate once the AI starts to move.
Then you could have the "regular" autosave save at set regular intervals ... alongside it (as it is now)
This new Autosave function could be called "battle autosave" and its default could be off but you can set it to ON in the options.
What do you think? 
