Living full time on an RV with a part time child?

My husband is considering selling our home and buying an RV to save money. I have always wanted to do this since I am naturally nomadic and so is he. I love our home, but financially it is not ideal to get any kind of retirement saved up, and with costs of maintaining it has become more of a burden in the last year. We have found one we like for about 20k which we can buy outright and pay off most of our debt after the house sale. The RV has all the amenities we feel we need like a washer and dryer, larger bedroom space, etc. We would be able to save almost 20k a year by moving in there. My step daughter lives full time with her mom and we have her every other weekend. She is 11 and wants to be with us all the time when she is visiting, she would sleep in our room if we let her so space wise, I don't see it being too much of an issue until puberty but even then who knows. She is very secure in BC with her mom and grandparents (she has her own room in both homes and ours now currently) and has no plans of moving down to live with us full time, so we are keeping a home we really cant afford to accommodate her 30 days a year? In theory I think we would both be happier having less debt, we could take trips to wherever when we have her and on the off weekends, we could drive up to BC and stay to visit her. Also I could create a space inside the RV for her specifically.

Anyone have any insight into this situation? Thanks
Added (1). We have discussed that if she is unhappy in the RV we can always get into another place. We have discussed it with the child and she got very excited about it because of the mobility, she loves to camp as do we and would every weekend if we were able to. We are planning on discussing it with the mother so I suppose that would be the only thing that would stop this plan.
Added (2). Also in regard to Casey, we are paying out 70% of our income. By getting out of the mortgage we can save 2500 a month so if there is any issues, it wont take much to fix it compared to spending the next 10 years just trying to get out of debt. We have 2 vehicles that can be utilized as well so in reality we will be spending only about 700 a month, which is what we spend alone on food and utilities now. We have a free place to stay as well. It doesn't mean we wont have another house later.
Added (3). I understand some of you believe 11 is puberty, but not all kids go through the change that early. She is VERY little emotionally still and very needy still. I am just looking for feedback on people who have been in this situation with kids even for a weekend. I don't need financial feed back, just on having kids in an RV. We only get her from Friday night at 8 PM-Sunday at 12, the time is VERY short.

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