Well, it sounds like Harper is a month away from really doing this. I don't think they'd start playing Guthrie every day. Or Pache either but an elite defensive CF would certainly be a better option (and if his bat comes around even better).
Regardless Harper and Bohm both play every day so maybe Harper plays 1B half the time and DH half the time, and Bohm is either DH or 1B otherwise. Really, I don't think Bohm's bat is so strong so he has to play every day, and Sosa's bat has leveled off to where he also doesn't have to play every day. But Harper and Schwarber and Castellanos do (even if Schwarbs has been disappointing).
I also gotta think they could just play Sosa instead of Guthrie (at any OF position) if it comes to it. But right now Sosa's bat is weak enough that Guthrie isn't really a downgrade per se. They are both guys with small sample success that's probably not sustainable, so c'est la vie.
The way things are going right now you could start giving Sosa one start a week at SS if his play demanded it, though it does not currently.