I don't like the idea of moving positions on Turang and Ortiz for a platoon bat that will likely be a utility guy after this season. Just seems like too much MLB the Show thinking.
Put Hamilton at 3rd and he should be fine there if he is as good defensively as the metrics claim. Hamilton has a stronger arm than Durbin so that shouldn't be a concern.
The team absolutely needs to find a platoon partner if they plan on making Hamilton an every day guy. He should get very minimal at bats against LHP. If the team is against a free agent, which I think they shouldn't be, then you have pretty limited options.
If you are worried about service time, you probably just bring up Leonard who has decent numbers against LHP. If you aren't worried about service time, Williams has pretty good numbers against LHP.