By the time you're done, depending on what you put back into it, it will have less formaldehyde (or other material) off-gassing than a new trailer.
For Hohenwald and others curious about reasoning--I gutted mine and rebuilt it because I wanted something I couldn't buy, a highly insulated TT that had appliance efficiency. The decision was made before I started to buy a trailer with "good bones" because I knew I wouldn't have the heart to demolish a good used one. I accomplished my goals and the total cost was lower than the price of a good used TT (not considering labor).
This sort of project isn't a good undertaking for most. The skills have to be there and, as Cruiser states, you need to have a long time-frame for completion. Most folks would rather be camping than building.