It would be very tough to get enough playing time for Youk, Ortiz, Teixeira, and Lowell. None of these gus are platoon players. They all play 150+ games a year. when healthy. If they have injury situations like Ortiz, Lowell and Drew had last year, there would be no problem. Youk could even play some left field in Fenway if Bay could play some RF.
Edit: If they sign Teixeira, someone would have to get traded. After the injuries from last season, Lowell's and Ortiz's value would be way down. Why sell low. The best trading commodity would be Youkilis. He's approaching his FA years. He may be difficult to keep anyway. He could net the Sox a really good player in return.