Running weakside platoons in both LF and CF is perfectly fine as the roster currently stands, so long as Marsh starts hitting RHP like he always has. Assuming that happens, and if Kepler is no more than he's shown so far (99 OPS+) we may yet see Crawford in July, with Marsh (and perhaps a bat upgrade on Wilson if he doesn't thrive) in LF. Or they could get a new LF and live with Marsh/Rojas in CF. The RHB-shaped hole in the line-up is huge no matter what, with three negative offensive players right now, and Casty unlikely to stay at his current level even if he's still decently above average (at the plate).
If Marsh can't find his bat at all you kind of just have to play Rojas more in CF for now.
Not that it's really cost the Phillies any games but the back-up catcher spot has not yet been an offensive upgrade either.