roller coaster 8 is a twin axle. Do you mean a roller coaster 8? Which is a single axle.
I don't think they make the Roller Coaster 8 anymore, but only because it's been superseded by the 8.5.
Roller 8s take just over 1000kg, from memory, so plenty over spec, but if you got it for a good price then be happy, they're great trailers!
Don't forget, if you go up in RIB spec, you won't have to change the trailer!