I think this should be the move when Lewis is ready. Miranda can fill the Solano role as a better version with options with some help from Farmer. Lewis full time at third unlocks Farmer to move around the infield as originally planned. It also makes Castro a bit extra but with the option he can be part of the last man rotation with Miranda. Gordon will soon become a road block as well. I would love to swap him with a Helman, who is RH, can play more spots, run and maybe even take a pitch and has options.
I actually don't think Castro has been horrible. With his role as an emergency fill in everywhere and enjoy the bad matchups guy he's been OK. They rely on him for things other than stats. I'd put Helman in this spot along with Farmer, Miranda/Castro and Jeffers to round out my bench. I guess this sends Larnach back down when Kepler is healthy. Yuck, tough choices but good problems. Part of why replacing Gordon with someone with options is important.