Richard -- Thanks for the analysis. It left me with some more questions, but I did follow your explanation well enough to give the edge to green, a color that appears to be a good compromise to achieve the goals I identified.
Guess that means I'll have yet another green shelter.
Questions I have after reading your reply are partly due to my lack of aptitude for digesting scientific notions, and partly due to my tendency to sometimes assume more complexity exists than is warranted.
For example, I don't understand how to reconcile your statement on the one hand that blue absorbs less energy than green because blue has a shorter wave length with, on the other hand, your diagram that seems to say (at least to me) that a shorter wave length leads to more energy. Since blue is to the right of green, the same direction that is indicated by the diagram for shorter wave lengths and more energy, it seems that the diagram is saying that blue has a shorter wave length and would aborb more energy.
Your analysis also caused me to wonder about the features of gray as described at Oware's website -- specifically Oware's statement that the gray color of its tarps (which is not a dark gray, but relatively light-colored) "lets radient heat through in hot weather (doesn't give very dark shade)". It seems to me that the above statement at Oware is just a more concrete expression of your general scientific statement that "[l]ight grey will absorb less sunlight than blue and dark grey will absorb more".
Am I correct? And, if so, does the fact that a particular color will "absorb less sunlight" mean that more sunlight will pass through that color as light? And also as heat?
By the way, I found no description of features for royal blue at the Oware website, and therefore no comparison of royal blue's features with the features of other colors. That's why I posted my question here.
As I indicated above, I conclude from your analysis that green achieves the best balance for both shade and quick drying than either gray or royal blue, and green will also be a more visible shelter than gray in snow while being a less obtrusive shelter than blue in non-snow conditions.
Maybe my shelter collection of grays and greens reflects an intuitive skill that I must have for picking colors for best all around use. But I did like that royal blue, too.
Thanks again for your information.