Towing triples with toy hauler

For those of you towing triples out there. Did you install the hitch on the trailer yourself? Did you bolt or weld it to the main trailer frame?

Did you connect the 3rd trailer plug wires into the existing plug wires for just the trailer lights or did you wire in the brakes too?

Does that pull voltage from the main trailer electric brakes or?

Wondering if or how that works on a 3rd trailer with brakes.

Just plotting a idea out and trying to get info. Thanks.