Generally, one or two people can live comfortably in an 18-foot travel trailer. For two or more people, a travel trailer that is at least 21 feet long is recommended by eHow.
Since travel trailers are configured in many different ways, including some that feature telescoping capabilities, sleeping capacity varies. Also, the number of people that can sleep in a travel trailer is not necessarily the same as the number of people who could comfortably live full-time in it. People considering travel trailer living must examine their particular needs in order to determine the number of individuals that can live in the allotted space.