1.) You may discover things you wish you hadn't.....like the previous owner's Swinger magazines stashed under the bed (eeww). Or evidence of critters making their home in the underside of the trailer.
2.) All of the old fixtures, cabinets and panels you plan to remove are permanently fastened by fifty thousand rivets.
3.) Everything (everything!) is curved, which doesn't make for easy cabinetmaking.
4.) The lights and turn signals never work properly. Sometimes only the turn signals work, sometimes just the running lights.....sometimes using a turn signal turns on the running lights (seriously, this has happened to us because of a grounding issue). It's an evolving mystery we have yet to completely solve.
5.) There is nowhere to hide....even our very small airstream is much to big to fit into a garage. And the silver finish isn't low profile either. For city-dwellers like us, our little project doesn't exactly blend in. Make sure you have friendly and tolerant neighbors.