GVWR does matter legally, you can argue the axles hold the force down but you can't say you can get it stopped or the truck will perform as needed. To me if you have a toy hauler with a hitch weight of 1500lbs and you only have enough payload left for 500, you are hanging yourself out to dry if...
You are actually really overloaded.... 3640+4180= 7820, your GVWR is what 7200 (look at your window sticker or the little white sticker in your door)? Will the truck fail, probably not. However, if you are ever in an accident you could easily have a civil suit on your hands.
They said 5000lbs...