Worthwhile to create some 'building block' PCB instead of handsoldering?
You've got 4  output boards that are essentially identical.
If you design an output board that mounts directly onto the power supply module they can be exactly identical and do not need any jumpers 

You could probably do the input board on the same PCB design by adding another DIP8 outline with pins 3 and 4 connected differently and add pads for the indicator LEDs too.

Then the only interconnect needed is the signals to the opto-couplers
and the connections to the DMX jacks.

I don't think you need a full 3W to drive an RS485 line, more like 0.5W (at 5V drive) I'd look into isolated DC-DC converters eg: B0505LS
then you could run the whole thing off a single 5W supply