Hi
"However the output will then be a mix of tracks in mono."
Just to check on what I said here re the output of split channels being in mono.........I was wrong! 
I have split the channels in a test stereo clip from Youtube and saved them as LEFT and RIGHT .wav files.(They still played right and left sides so I was becoming doubtful regarding my statement). I reloaded the clip, muted the original track and then loaded the Left and Right channels wavs to Audio track 2 and Audio track 3.
You are correct Borate, the exported clip played OK in stereo. 🙂
Ametz now has his answer. He can split the channels (I actually used X-oom Music Clean to do this) reload them and edit them on separate tracks in VP.
Nat