It can work, but as with everything, it really depends on the people involved. My first wife used to like to drive support for me since it got her out on the event without her having to ride her bike. In fact, on BAM (Bicycle Across Missouri) in '85 it was 566 miles in 60 hours and my ex and my ex-boss (also a woman) drove support for me. So that was great, and they both had a good time with it.
My present wife is also a doubles rider (in fact, she got me back into ultra-marathon riding), and in most CA Triple Crown events a private SAG is not allowed, so we work some doubles and ride others. If there's too much cilmbing for her, she works the double while I ride it (so I see her at checkpoints or at SAG stops).
So there's no easy answer that will work for everyone (sorry!).
Rick / OCRR