That Rover is really sweet! I saw that here before. I just want to drive that around Just to show it off, I wouldn't want to get it dirty or scratched.
However, I was thinking of the splitter mounted parallel with the front of the trailer bed, probably just horizontal. You could use the box area for the motor and pump, etc. Here in Nebraska you don't need trailer brakes if it's only a single axel, I think under 5k or 3.5k, will check before I build. You could build a 10 foot trailer and use the front 2 feet for the splitter and set it up so its not too toung heavy. Of course thats if you start from scratch or a frame, not using a truck box trailer. I saw an old box trailer on CL for 150 bucks so I was just thinking. I should stop that habit and just fab something. After all I am just doing this for something to do in the off season, tree trimming. I really would like to use a box trailer to keep it cheap, those are pretty heavy duty anyway.