I got my trailer late March this year and here is what happened:
From the starter kit I used the water hose, the water pressure regulator and the 30A to 15A adaptor.
The sewer hose that came with it was not complete so I bought a Camcor 20' kit that came complete, including the transparent elbow and adaptor.
My recomendation would be to get the camper with the starter kit and then check what is missing (I have two 30A/15A adaptors because I didn't follow that
)... anyway below is the list I made before I got the camper and my comments after I have camped:
in line Water filter => not needed, the camper has one
25' drinking water hose => It comes with the starter kit
Adjustable Water pressure regulator with gauge => It comes with the starter kit (not adjustable but..).
30 amp surge protection => Haven't bought yet but I will
30amp to 15amp adaptor => it comes with the starter kit
30 amp to 50amp adaptor => Haven't bought yet but I will
20' Sewer hose kit => Mandatory in my opinion.
20' Sewer hose support => Mandatory in my opinion.
10 Pack Leveling Blocks => Mandatory in my opinion (Have used every time so far).
Chocks => Mandatory in my opinion.
Towing Mirror => Mandatory in my opinion.
Also, to buy over the internet is way cheaper than at the dealer store per my experience.