I'm planning my first bike trip across the country for next year and am confused about which sleeping bag to buy. After a lot of research, I like the Marmot Arroyo, but I am not sure if it may in fact be too warm for summer riding. I am traveling from west to the southeast then up the eastern seaboard to Maine. Would a synthetic bag be better? I've studied the pros and cons of each, but getting feedback from those who've been there, done that, is most important. Thanks.