I'm with Ned in thinking that a park model might better suit your current needs. With four of you there will be more living space - more like a house. Having a motorized vehicle sit for two years might cause unanticipated problems. For example, rubber hoses dry out, tires dry out, an unused engine is more likely to have issues, etc. In case you don't know about park models, they're basically trailers that are meant to stay put. There also are some very nice double-wide trailers that again are meant to stay in one place. For a family of four, I should think one of those options might be better than either a travel trailer or motorhome.
There are also monthly cost differences in where you park. With motorhomes and travel trailers you would be in some kind of RV park, some of which can be quite costly, especially over a couple of years. Park models also tend to be in RV parks. On the other hand, double-wide "trailers" are found more frequently in what we call mobile-home parks. Some mobile-home parks also accomodate short-term RV visitors, but most RV parks do not accomodate mobile homes, mainly because you don't move a mobile home on a regular basis. Some of these places are a mish-mash where anything goes. It kind of depends on what's available in the area you'll be attending school.