I had a similar issue with my Fleetwood Terra LX and found that window weather stripping can help significantly in reducing drafts and improving insulation. However, to take it a step further, I also installed window shades, which made a big difference. Not only do they block out more cold air in the winter, but they also add an extra layer of protection against the elements. The shades work in tandem with the weather stripping to help keep the interior of my RV more comfortable, especially during extreme weather conditions. If you haven’t tried adding shades yet, I highly recommend it for both insulation and privacy benefits!