Well it was a simple straight forward question. No, I don’t have a surge protector.  I’m wanting to add one. The space available just seems unaccompanied to fit one in.  A previous owner has added a charge wizard 4 stage charger and has done some unconventional wiring to fit it in.  So I’m looking for a workaround.  Best thing would be to have a 2552 wiring diagram. 
I feel your pain cuz, wish I had an easy answer for you.  If there are factory wiring diagrams for the PC's coach area, I cant find them. Add the previous owner ""has done some unconventional wiring"" you are now . 
What you got in your skillset? Initially, with your question about the 50A, you appear to not even know the basics about a 240V 50A power outlet. You even doubt it is 240V. This shows a basic lack of electrical knowledge, what type of multimeter do you use when diagnosing things? 
Now you are asking for detailed answers about an 'unconventional' system.  

 'Unconventional' in what aspect?  Thats a rather worthless descriptive term.   

  But hey...peaceful thoughts, right?   

I am googling xantrex 1800 to try to help. since you have not provided a model number of what you have, lets guess this?? 
http://www.xantrex.com/documents/Power-Inverters/PRO-Series-Inverters/975-0263-01-01_Rev-C(artwork).pdfOK... You want to add a surge protector to..... Hm... you didnt say. 
Anybody with 50 amp and the 1800 xantrex have an internal surge guard?
Well, the question at face value seems to ask if anyone has an 'internal' or '
hardwired' 50A surge guard. Google either of those and you readily find something..
Like this? 
https://www.campingworld.com/50-amp-power-watchdog-bluetooth-smart-rv-surge-protector-with-automatic-shut-off-emergency-power-off---hardwired-version-117412.html?gclid=Cj0KCQiArozwBRDOARIsAHo2s7tEGJ9lMPlgk7i-Uesxa0ey3mv6xo7NCTML1ECzF2mlqBI7UYBMEj8aAmSBEALw_wcB
But your question specifies the Xantrex 1800 inverter.  So maybe you are referring specifically to a surge guard for it? If so, for the 12V input, or for the 110V output from the unit?  

If ""
The space available just seems unaccompanied to fit one in."" as you say... (maybe autocorrected from unable?!? You doing this on a phone?)  then its just a matter of running a remote feed to an area that will be able to house the surge protector. Thats an 'eyes and brain' exercise on your end. Or pay someone that can do it. 
There is help here, but if you want to be a smarta.....snarky player, sorry.  As you see , your question is about as clear as mud, and keelhaulers reply about the 50A service being irrelevant to your request is pretty friendly, and possibly enlightening to you. Likewise the wiring diagram, even though his does not have 50A service. May not be a meaningful difference. Up to an informed tech to decide. 
Maybe post a picture or two to enlighten us as to what you need.  

 Help us help you. NOBODY here wants you unhappy with a PC. We want to help.  

You want to truck south to Melbourne FL area, I will try to give you a hand.  i95 exit 173, +10 miles.   

  But keep your cool.  
