One section at a time.
If you are at the door, all you need to wax is that door. Nothing else. Don't drive yourself nuts thinking about the rest of the camper.
When you are done with the door, then pick a manageable section next to it... 3 or 4 ft by maybe 6 ft high. That is all you have to wax, nothing else.
When done with that, pick another section...
Keep going like this, one section at a time.
Then you are done!
This is how I do any big job - waxing, cleaning, painting, landscaping, whatever. The killer with big jobs is psychological... you basically psych yourself into uselessness because you concentrate on how big the job is, instead of just what is in front of you.
Oh, and have fun!