PS/edit.: renamed the title as it's really something that makes more sense from within scripts, not from the command line itself. Unless perhaps one makes a wrapper script that edits smplayer.ini with whatever parameters are set by command line and resets afterwards, while still somehow preserving smplayer's own syntax, if that's even possible.
Major edit:
Apparently the best way to go is to dinamically edit or switch/rename the smplayer.ini file, in the following...