I have a great three season tent, Northface Tadpole, free standing, easy to put up, lots of space and very good in a downpour but when the temperature goes down below say 38° F it gets uncomfortable outside the sleeping bag. A four season tent is too warm in the summer months and twice the weight of a three season tent. There must be a convertible tent that can be breezy in the summer, (and bug proof), but warmer when the temperature falls. Northface should build the Tadpole with a little less ventilation screening, that may work. Anyone else have a problem with their tent when the temperature drops?