personally I have always had 4 wheelers & always will. Just about to spec up a new trailer for my new boat & they are going to make me a bespoke 4 wheeler to take a 5.5m RIB, the normal production 4 wheel models don't suit a RIB of that size without a load of overhang at the back & front. You need to set it up so the rear most rollers are just on the invert of the transom, whilst still being able to setup the winch post at the correct height etc. The rear most roller also needs to be the rearmost part of the trailer, i.e. the end of the cradle needs to project past the ends of any side beams, that way, the first thing the boat hits when recovering is the cradle & not the trailer structure, especially if it's a lumpy recovery. When all that's said & done, you need to be able to adjust the position of the axles to balance the whole outfit & get the nose weight correct. Very easy to get a trailer that's too big, especially where RIBs are concerned as the LOA can confuse matters.
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4: See rule#5