For what distance, at what speeds and in what kind of terrain? If it is a short distance you may not have to modify the trailer but for a long distance at high speed you would likely need to. My first concern would be the size and location of the keel rest. Once you load the boat on the trailer you lower the keel so that the weight rests on the trailer and not in the hull and bunks. This rest which will be in the center of the trailer may or may not be in the correct position for the Catalina. Perhaps a 2" X 4" properly positioned may do. If the bunks are not the correct height the boat may lean to one side or the other. The center of gravity of the boats may not be the same so you could have some tongue weight issues which could be addressed with an adjustable hitch. The best way to find out is to load the Catalina on and see how it does. We trailer a 22' Starwind which loaded with the outboard motor and boat stuff weighs around 2,800# in a single axle trailer. The boat is balanced on the trailer and the tongue weight is carfully adjusted to prevent sway. We have 14" tires for trailering and a spare. We trailer long distances and those tires get hot. We inflate them to its maximum as they will run a little cooler. We usually stop around every 100 miles and feel the tires and the hubs. If the hubs are to hot to the touch we will allow them to cool before continuing. These boats are heavy and a single axle trailer will barely do its job for long distances. We repack grease in the hubs after every trip and also carry with us a spare set of bearings. Usually a tow of this weight would require that the trailer have brakes but most single axle trailers don't. We tow with a full size SUV which has adequate brakes. The sides of the hull may flex or cup if unevenly supported in the bunks. Once again it should be ok for short distances but not recommended for long ones. If the bow stop does not align to the catalina just run a strap to tie it down. Hope this helps.
