I wish I didn't know so much about this.
Trailers have gotten a lot nicer in the past few years. Now they have real r12 insulation, 2x4 walls, vinyl siding, and a pitched and shingled roof. The 1980's trailer I grew up in was nice for its time, but it had none of that. You can get those features in trailers made in the past fifteen years or so. And I recommend them as minimum required features.
But trailers are still trailers. I actually had a job delivering new ones last year. They are meant to look nice, at least for long enough to get people to buy them. But then later, you start to notice that everything is plastic and cheap, and as crappily made as they could possibly think to do it. Also, you can't have finished drywall, because it cracks when the trailer is on the road, so you have these annoying paneling strips to cover the drywall seams.
Tornadoes are the biggest problem. If you live in a trailer, an f1 will kill you. It happens all the time. You need a storm cellar or underground spot to hide.
If you buy one, get something at least a few years old, but not so old that it does not have the stuff I said you want. And pay cash if you can, or finance over a short term. Trailers are like cars, they tend to depreciate over time, but it's much faster when they are brand new.