Syncing the audio shouldn't be that hard if you can see the wav forms on both the audio sources matching a peak somewhere...that said if I could give you a couple pointers the next time you do this:
-starting and stopping the recording on both sources (camera and the audio source) as close to each other as possible (if they are not physically close together give the other person a visual 3 second countdown)...not a big deal but it makes post easier.
-after you start rolling have someone clap their hands in view of the camera (like a movie clapper) then use that peak to sync.
I've had to do this quite a bit over the years to sync up multiple cameras along with the main audio source(s)...once everything is on the timeline it takes only a minute or two to sync.