I wouldn't butcher those pretty walls for NOTHING. That wood is gorgeous.
I think insulation can have it's advantages, but there are plenty of people out there camping in teardrops without it and they are perfectly happy (and comfortable).
I insulated mine, but if I had it to do over again I wouldn't. It cost me a lot of extra time and money and I doubt that the difference it makes will be proportionate to what it cost. If you ventilate properly that will take care of your condensation problem and if you're not camping in extreme temperatures, I wouldn't worry about it.