If by "converter box" you mean the type that is powered separately from the battery and the signals for actuating the trailer lights are taken from the lights, then that's the type I perfer and have installed on my truck. It has been in operation now for about 10 years with no failure. Using this type takes the load away from the light wiring and flasher unit, but you'll still need to tap into the light wiring.

92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles