Greetings Belinda!
The chairs to the right actually represent the front seats, so the camper part is 8' in length. Yours would just be a foot narrower, which would still work out okay.
A few thoughts... If you're building your cabinets, consider sliding doors, they don't require any extra space to open... They are also easy to secure while traveling. If I'm building an interior from scratch, I even put all drawers behind sliding doors, it's a great way to secure them. (I'll get store bought sets of plastic drawers, and then build the cabinet accordingly.)
A built in bed with storage underneath may be a good option, and a bolster could make it comfortable seating while at your desk.
http://www.amazon.com/s?ie=UTF8&field-keywords=bed backrest&index=blended&link_code=qs
Your rocking chair could also probably fit just inside the side door, facing backwards, with access to your desk.
The back doors can be made to open from the inside fairly easily, I've done this on several units for others. Even if you're bailing out over the top of cabinets, I would still want that option.
While smaller can be done, I have to say that I am huge fan of 15 passenger vans with high tops. This is the most comfortable home I've ever had, and if that means a little lower MPG then so be it. I'm still saving a fortune over a house or apartment, and I'm not sacrificing any comfort in the process. I've got a kitchen, a bathroom, a living room, and a bedroom. I've got heat and air conditioning, all the power I want or need, and a view to die for, that can be changed any time I choose. Even if I could get double or triple the MPG, I wouldn't take it at the expense of comfort.
Life is so short, and the additional cost of comfort is so low, that I believe that every van dweller can afford that comfort, and deserves it.
Cheers!
The CamperVan_Man