Small panels have their place but I've always figured you should rate the solar wattage to the power you plan to use during the night as well as the average daytime load and the battery rating. If you go small you might want to look for something that's expandable. So the controller would have to be rated for add on load.
Dave
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2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer