Having the game create autosaves something like every 1000 (or maybe even every 100) turns could make finding various bugs in the game and in scenarios easier ("where did I get this special item that I am not supposed to have?" for one example).

So I think we could have an autosave directory, with filenames like

(timestamp)-(some unique id derived from party member names - first name letters?)-(scenario name)-(stepxyz).sav

EDIT 1
It would probably be beneficial to include some identifier of the openboe build that created the savefile in the filename - perhaps the git commit hash that's used at the title screen.