Even if it will pass smog in California, you will not be able to register unless it has a US DOT sticker. I just gave up trying to register a 1983 Hymer motorhome with a Mercedes 2.3L gas engine. It has been registered in Wyoming since 2009.
I’ve been comparing pop up campers for a while now. You’re onto something with your portable cooker and frug idea. And so many pop ups even hig( priced ones don’t have a head. I’m too old to trek across a campground I. The middle of the night just to pee. Seen our at overland expo.