Hello Richard. I'm 6 foot and have just returned from a trip to Portugal, Spain and France with my pertner. She was not with me all of the time and slept downstairs and up and when its hot upstairs is the place of choice because there's a little more room and a bit more cool air (but when it's 28", not always).
I have no problems length wise and no problems width ways either.
The California is a brilliant vehicle, versatile and so well thought out. We cooked some historic meals and always enjoyed lovely chilled wine too. It eat miles and is comfortable too.
We have had ours 10 months now and every time we use it we are still amazed and enthusiastic about it's potential and performance.
This week I did Algarve to Evora, Evora to Burgos via Salamanca, Burgos to Bilbao and the Guggenheim museum and onto St Jean De Luz followed by a day on the Ile De Re and finally after a stop in rural France onto the ferry last night. Each night wild camped and sometimes I cooked, others ate locally. However, I suppose my point is that it did it effortlessly, each night was enjoyable, warm and a pleasure.
I think they are expensive but if you use it you will love it.
Hire one first and I think you'll be blown away.