I sold my Tow-V-Aire long ago, so going from memory. It's made to lug to a 12v socket back in the day when they were still cigarette lighters, so 10 or maybe 15 amps is the most those outlets could provide.
If it plugs to a dashboard outlet, the outlet is protected by its own fuse anyway, so there isn't much risk. But if you have installed an outlet just for the toad brake, then you need to be aware of the wire size used to install it and the rating on the outlet. Most outlets are in the 10-15 amp range, though.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL