Dennis,
From your description, it sounds like you either have a short or a defective alternator. The highest probability for a short would be in the wiring going to the toad unless it was fused to protect the wiring. If you can disconnect the toad brake wiring without disconnecting the lights on the toad, that would be an easy test to see if towing without that wiring connected stopped the problem.
Otherwise the problem will probably get worse, and you will need to correct it. If you can come up with a better description of when the problem occurs and under what conditions someone may be able to offer you more help.
Gerald