To me, the unique configuration of Fenway's CF, and the need for a stronger-than-normal arm in CF (and RF) make moving Beni to CF very undesirable.
On platooning him. I was calling for that before his offensive decline.
Even his best season (2018) showed the need to think about a platoon:
vs RHP: .877
vs LHP: .694 (not God-awful, but still the best he ever had, other than what might be seen as a fluke in 2019)
2016: .984 v .429
2017: .813 v .622
2019: .764 v .796
Career: .821 v .691
Now, people have pointed out that Yaz had a career OPS vs LHPs of .692, but he was an amazing defender. He also hit lefties much better earlier in his career, so maybe the platoon idea might have made some sense later in his career, but with a HOF'er, it's a tough choice for a manager to make without making waves. (Also, it's not like the Sox had many better options vs LHPs back in the 60's and 70's.)