Just book the 1-stop and hope for SDC availability for a ps route (LAX-SFO-BOS or LAX-EWR-BOS). If the timing works for you, there's a 777 flying LAX-DEN, and a dreamliner flying LAX-IAH. LAX-IAH-BOS would get you two meals, which is a decent alternative to ps if there's no SDC availability for ps.

I did just this last week Booked LAX-IAH-BOS, SDCed to LAX-EWR-BOS.