I spoke with the guy, it's homemade and apparently works great off road behind his Rubicon. I think it's a deal, the ARB tent runs to $1200 on it's own. Here's a pic of the inside, just a shell, would make an awesome project, other trailers I've seen run into many thousands of dollars.
I like this idea, not easy to find a used generator/light tower trailer for a good price but one just needs to keep in contact with rental yards and big construction companies. If I come across one of these it would be a fun project, I see a storage area, kitchen, cooler fuel area in the front, the ideas are endless. Up top can be a tent or bikes, kayaks, whatever. Look out rental yards here I come.