It looks like some of what you are calling "rot" is stained wood where it has been in contact with water. If the wood is still intact and is not breaking down, you don't have to replace it. There are methods to stop any future breakdown and there are epoxies that will reinforce slightly damaged areas. What I did was to replace frame that was beyond repair, sister new framing when applicable, and after all was solid, sprayed a bleach solution over everything.
FWIW, I restored a 22' TT ( that saga starts
here) and the framing was easy. The most labor-intensive part was cutting and installing the 400 pieces of insulation board that replaced the factory insulation. It was the most work but proved to have the best return on time invested. I can heat the Starcraft with a small electric space heater and it is very comfortable.
One piece of advice: draw out plans for what you want to end up with, first. Electrical, plumbing, mechanical systems should be thought out down to the wire. The plans don't need to be as good as the Lance drawings, it's the exercise of the thought that goes into the plans that results in a good job and less labor. Disregard this if you know exactly when, where and how to install the coaxial cable for TV and router repeater wires and can hold all of this in memory, lol. I replaced the complete electrical, plumbing, and mechanical systems. I had to open one wall section to add a forgotten receptacle location and had paneled over one switch location that didn't get cut out.
Good luck on your project, the best thing you have going is your attitude. it's better to not have a deadline to meet.