Follow-Up:
We lived in our 1999 Rialta QD for 4 months during which we went to Alaska. There were just 2 of us, but found it comfortable. We had experience however in earlier years taking our 12 year old daughter for 10 weeks in a VW poptop camper (westphalia) and seemed to survive quite well. If you plan well and I might add, have an awning so you have entended living space in bad weather. I think it may be tight but it would be possible. Allow space for your daughters favorite things and try to convince her to take small but favorite things. Sometimes a small tent comes in handy to allow your daughter her own space...and they only take up a small space in the Rialta.