With 4 seasons capability comes weight. About the best is Lance in regards to lighter weight and 4 seasons. The thing about 4 seasons is it's a term thrown around rather loosely IMO. Our Fox Mountain is a so called 4 seasons 5th wheel. It doesn't even have dual pane windows. What constitutes 4 seasons is that the holding tanks are insulated and heated from the furnace ducting. It was 27deg last wed in the mountains where we were camping. Our 4 season unit got down to 40 deg over night with out running heat. I wouldn't call that a 4 season unit. Had we had dual pane windows, R38 in the floor and ceiling and R16+ in the walls I believe it would've been warmer. Also typical RV construction leads to gaps in any exterior penetration. those need to be rectified in order to fully use the higher R values.
