Over the past year I've learned that my solar setup—a 270W panel and two 104Ah batteries—is sufficient on most days. I need to be very mindful on short, overcast, winter days, or whenever there are several overcast days in a row.
Under the right conditions a wind turbine can charge even in the dark. That's neat. The problem is, wind turbines like to be big and high off the ground. When using a turbine and tower and support cables and stakes and wiring and whatnot that disassemble compactly enough to stow in a van, those necessary conditions are often fleeting and the output minimal.
These photos are from a 2011 article about setting up a workable mobile wind turbine. Note the turbine is about as big as his leg and the blades are each about two and a half feet long. There are also two 8-foot sections of schedule 40 1.5" pipe and other space-consuming stuff. The owner of this setup lives in a travel trailer. Between it and the tow vehicle he has room to store everything. The man who wrote the article lives in a converted cargo trailer towed by a van. With his extra space his view of what's compact is different from mine.
But I'll keep investigating the possibilities. Maybe there will be a tiny, super-powerful, affordable wind turbine someday.