You really only need a simple trailer to which you can add transverse beams and cat cradles. I used a jet-ski trailer (the double-wide size) and adapted it to a 20ft cat.
I know of many who converted old galvanized boat trailers to cat trailers
I second that. You can use any almost any trailer with very little extra work. Last week we trailed a Supercat 15 in a motorboat trailer and it was quite easy.
We tied to the trailer two transversal beams, wrapped eva foam where needed, tied the boat to the beams and to the trailer structure and left.
You can use pipe, timber or whatever is strong enough and the right size for the beams, while most school supply stores sell EVA foam.
You can fix the beams to the trailer later. Or never.
Good luck,
Luiz
