I don't live in a trailer, so I can't help much there. That said, like
@genny mentioned, from what I have been told by students living there, most of them either have familial/spousal support or are take out additional loans in order to purchase one. Honestly, it's not really
that much cheaper than apartments in that same area. For example, I am currently living in The Grove apartment complex, which is about a mile from the school (so I walk to class to save on gas expenses)---some students refuse to live here because they think it's "undergrad-centric" and claim that there's too many parties/events, etc., but I've personally had no issues with loudness or anything. The big benefit is that I pay $580/month... and that's it. It includes rent, utilities, internet, cable, and amenities such as the pool and gym. It also pays for any maintenance that I need done on the apartment. With the trailers, from what I understand, you generally will pay less in rent but you do have to pay separately for the utilities, water, electricity, internet, etc., so in the end it is probably on par with if not more than what I am paying for an apartment. And you'd be on your own for most repairs and whatnot; some people are ok with that, but I'm not and I would just rather not have to worry about it.
There is also Copper Beach, which is owned by the same company and right across the street from The Grove. If you're adamant about wanting a 1bed/1bath apartment, it is a great option (The Grove only does 2bed/2bath and 3bed/3bath), but they can be a little on the pricier side. Don't quote me on this, but I have a friend there in a 1bed/1bath and she is paying somewhere from $850-1000/month. If you're relying solely on your loans for living expenses... that is going to be really, really tight as generally you only get a little over $6000 back each semester. If you can work or have a spouse who can, that would help, though. Both The Grove and Copper Beach are pet-friendly.
There are quite a few apartment complexes in Ames, some closer to the school than others, so there are lots of options!