Our kitchen too runs along one side of the trailer.
The Drifta kitchens and storage boxes have polyurethane runners which when on a flat smooth surface, run very well with little effort required to move them.
Our problem, was that we had the trailer galvanised shortly after manufacture, which as with all trailers being galvanised, the floor warps with the heat of the galvanising process leaving 3-4 high points along the length of the floor
This along with the texture of a checkerplate floor results in the polyurethane runners being torn to shreads when either the kitchen or storage box is slid along the floor.
The fix was to secure to the high spots on the floor, 4 lengths of quite thick aluminium angle which provides a nice flat, smooth surface whilst also stopping the kitchen and storage box from sliding sideways when things get rough.
Didn't cost very much in both time and money and works a treat.
I have pics of the runner system at home, but I did contact Luke from Drifta regarding the issues I was having at the time and he posted both the solution and the pictures I sent him onto his website.
Scroll down to the bottom of the page.http://www.drifta.com.au/settFAQ.php
Hope this helps Neil.