Been there, done that! Ha ha ha ha First time I "attempted" to wax our first fifth wheel I was younger and it still turned into a HUGE task.
Like others here have said, plan your work and work your plan. I usually do the front and almost one side the first day, then depending on how I (my arms & shoulders) feel after that I try to do the remaining part the next day or two. It is very rewarding to step back after it's all done and admire YOUR handy work!! Think of it this way, after washing and waxing your RV you won't need to go to the gym for a few days. :B
Good luck and hang in there, it's doable just take your time.
Dan