While you have the sides off, might as well pull the nose off and fix any rot around the window. Or you could remove the front window entirely while you have the nose off.
The other thing to consider is replacing all of the fiberglass batt insulation with foam cut to a tight fit. Use window expanding foam to fill in any cracks. You will have much better insulation and will notice a huge improvement.
Good luck with the project. It can be a lot of work but will also be very rewarding in the long run.