[ricm]

A friend of mine did exactly what Tracy suggested, but found that the lights on the first trailer worked at different brightness when the second trailer was plugged in, and the lights on one trailer were brighter than the other when the trailers were connected.

The MFU is very fussy about how many LEDs it will power directly. There is another cost effective solution, using opto-couplers, but it requires some electronics know-how to design and build a small control circuit. It uses the light signals from the first trailer as switching signals to control the lights on the second trailer ,which will have an independent power supply. That way, LED brightness is always consistent and the MFU is protected.

Let me know if you need more help