What size feeder do I need for an RV shore power panel?
Where the electrical supply for a recreational vehicle site has more than one receptacle, the calculated load shall be calculated only for the highest rated receptacle.


clinches it.   However, this presumes this is one site.  If it is reasonably plausible that this is 2 sites, and Junior could roll up and park his TT30 right next door -- then yeah, you'll have a problem.  

And I would address that problem by fitting a generator interlock so both the 50 and 30 can't be on at once. I wouldn't worry about the 20.  

Also, build a birdhouse with a door over that thing.   You'll thank me later (actually you won't though).