I am guessing you own the unit and haven't or want any payments. We recently made a "BAD" purchase as the insualtin rating was not what we expected. We bought a different unit with the upgraded floor and walls. I believe about an R-9 is about all that can be achieved in the walls. While slide toppers, shade, extra insulation on the windows etc. may help, I believe you will be disappointed in the overall outcome of trying to renovate to upgrade insulation. This is my opinion only and live in Arizona and use our unit year round traveling in all different types of climates. We have been as cold and windy as 18* to a high of 115* while in the coach and we fairly comfortable but the unit was smaller and more manageable. So There ya go, I would think about parking in the shade full time or maybe it is a good time to treat yourself to a new or newer unit. Good Luck & Be Safe ! ! !