Heat is what really helps with off-gassing of glues, vinyl, carpeting of any kind, paints, etc. Alternating high heat in a closed area with good ventilation will accelerate the process.
I also have chemical sensitivities which is one reason we bought a perviously owned Escape
. I would agree with the suggestion you consider a used Casita to assure that all the chemicals have off-gassed. Just be careful to find one that has been well cared for and has no mold, people with chemical sensitivities are often sensitive to mold also, perhaps that is the case with you or your wife.
had a minor repair done at the factory and I used heat to clear out the odor, it took almost 2 weeks. We then discovered a leak and through the generosity of Reace at the Escape
factory it went back for 'hospital' care - to get partially taken apart and dried out, then put back together, so I will once again help the glues to off-gas with heat and ventilation.
With a new trailer you are likely dealing with more than just glues. I would think the Casita factory could tell you what materials they use, but people who are not as sensitive are not always aware of the how strong certain chemicals can be.
If you want a new trailer another option would be to consider another make, especially a double walled trailer. The only new ones currently made that I am aware of is EggCamper
. Fiberglass would not have any off gassing so at least the walls would not be a problem, though there would still be glues in the cabinetry install and chemicals in the the foam and fabrics in the cushions.
Good luck in finding a healthy trailer for your retirement adventures!