move to a desert climate. AZ NV So Cal, Colorado, parts of Oregon are desert, etc
for mold sensitive people it makes a huge difference.
otherwise consider buying a brand new mobile home and/or manufactured home, no mold issues there for sure
basements are ALWAYS moldy, always. try to find a home without a basement if possible.
I disagree strongly.
It is indoor mold that causes CIRS. Dry places still have plumbing, icemaker water lines, and HVAC systems that can leak or get moldy.
I wouldn't move across the country without visiting the place and having overwhelming improvement of symptoms while visiting. Furthermore, mold is not the only biotoxin that causes CIRS. If you have one of the multi-susceptible. HLA-DR genes, you must also avoid cyanobacteria and other biotoxins like the desert fungus in Arizona and California that causes Valley Fever.
ANY home, old or new, can have mold. Newer construction is fast and cheap with no thought of quality. Building materials often get wet and moldy during construction. I have seen it. I've also seen brand new stores and restaurants with multiple leaks and brown ceiling tiles showing evidence of water damage.
Don't know why you think a mobile home can't have mold.
I DO AGREE about
Dirt crawlspaces should also be avoided if at all possible. That's the biggest problem in my house.
If you are chemically and/or electrically sensitive, you will also need to consider those issues when you move.