I have a friend who has towed a 17-foot
Casita travel trailer with his Town and Country minivan for at least 10 years now. The size works OK for him because he goes out solo, or only one other person.
If you are looking for family size space, consider pop-up tent trailers. Forest River (Rockwood/Flagstaff) and Jayco make several models, usually 12-foot box, that include a shower/cassette toilet combination unit. The dealers here usually order those models with that option. Haven't checked other brands, don't have dealers for them.