If it's original BB, now called Classic, you'll feel it apply when you stop the coach harder than normal.
Can you see your toad from the coach while towing? Either mirror or backup camera? We have a rear coach window, so I made up a "monitor light." It's an LED trailer lamp with Running and Stop/Turn elements. Power Outlet lights Running when the Key is in ACC, and by being plugged into that Power Outlet, there's Ground for the Stop/Turn element also. Hot side of Stop/Turn goes to the Brake Pedal Light Switch. The Lamp bungees to the toad's rearview mirror. This lets me see the toad's still there, the Key is in ACC, and brightens when BB applies the brakes. What I actually really want to see, is that the BB has completely RELEASED the brakes, shown by the bright Stop/Turn elements going OUT.