Big Ideas, Tiny Spaces (subtitled: 'UK-based site devoted to DIY vehicle transformation into creative travel, living and work spaces') is run by Feta Brown who built a camper van retreat in 2015 and now blogs about her conversion project. She describes it as "an adventure in small space design, project management, patience and child-friendly faux cursing when the neighbours' kids were around".
Her camper van - called Martha - is solar-powered and has a woodburner, sofa bed, kitchen and composting toilet. Of particular interest is her series of posts Self-Build Campervan Dream to Working Plan. Here's what she says:
On the journey to converting my van into a little castle on wheels there have been a lot of lessons. It’s not far wrong to say I’ve now built at least 3 vans: the two vans worth of practice, failures and re-dos and then the third one where everything works. My accuracy, speed and techniques improved massively as I went along - not only because of practical experience, but also because learning general ways of approaching design/build problems which could then apply to other challenges.Pictured above is Martha and the working Google Sketchup plan.