This question comes up regularly and ALWAYS turns into a contest of legality vs safety. To me, covering a potential break-away of the toad is what would concern me most. I don't care what the legal aspects are, but I dread the thought of my toad breaking loose and killing someone, no matter how remote the possibility.
When we had our Monaco Executive, we were 48,000lbs, towing less than 4,000lbs. I could never tell the toad was back there. When we had our Pace Arrow, we were 25,000lbs towing the same and could definitely feel the toad back there.
In both cases I had a Brake Buddy, but will admit to skipping using it for a few short trips behind the Monaco.
You're relying on 2 hitch pins and a few bolts to keep that toad fastened to the coach. Yes, there are safety chains, blah, blah, blah..... However the breakaway protection IMHO, is well worth the investment and setup time of having the braking system for the toad. Legality is just a secondary concern for me.
You will probably never have a breakaway happen to you, BUT........ What if???????