much more complex construction
Was it? I'd have thought laminatng wood over concrete moulds was potentially much simpler than at that faffing around with metal and rivets, plus the ability to fit it out inside "in the half" before sticking the bits together. Skills? Most of the aircraft factory floor workers were HO and minimally trained, was that a problem? I can see that this method doesn't lend itself to mass production in the same way - perhaps that was the limiting factor? I'm not up on Mossie industrial production problems!
As for two trips to Berlin in a night - that's a long day in modern jet with 30 minute turnarounds - granted you miss those at the destination in this case but even so it sounds a bit over ambitious to say the least.