Not found anything good yet searching. However I found out that you can save with 'Control+S' while in the campaign map screen. I'm not sure wether you save the game to autosave or to the saved game you loaded, though. It might be of any help. Yet, if you crash every turn, the game is still spoiled..

Well, while waiting, you might want try check out the Samurai mod. It's a mod for MTW, designed much like shogun. It looks very nice, and lots of people seem to like it, so you might want to play it as well. It has it's own forum here: https://forums.totalwar.org/vb/forumdisplay.php?f=105