I don't think those connectors are designed for outside use. They would also create 4 more connections per panel increasing potential trouble. I plan on having a pair of panels up front on the right and left sides and two panels toward the rear one on the left and one on the right side of the trailer. Your idea of combining each pair of panels and reducing the conductors by half make sense. The spec sheet for one panel says 4.62 Amps. Considering they are used it's safe to say they will never make that much in their remaining lifetime. 4.62 times two panels = 9.64 amps. My book says I can run 10 amps at 12 Volts on #8 wire for 18 feet. That is where the combiner box will have to live. From there I will take #6 down to the battery plant. You mentioned that your book says x amount of feet round trip. I didn't understand that. My book say "Maximum one way Distance for less than 2% voltage drop" The wind is really getting with it here. Light rain. How is it in Nevada?
http://i20.photobucket.com/albums/b2.../WireChart.jpg