Have you scaled these weights?.
If so, then you need to rethink what is alright.
A TTs TW can vary a lot in the course of a trip. Food gets eaten and leaves the pantry and fridge and ends up in the black tank. Water gets used and leaves the fresh tank and ends up in the black/grey tanks. Propane gets consumed and disappears as exhaust in the air. Many other things may shift around as well. So it you start a trip with only 10% TW, that figure can increase or DECREASE, as the trip progresses. Yes the hensely may be keeping it from swaying, but too light a TW is still not good. A TT is somewhat like a teeter totter on its axles.... You want the tounge to ALWAYS have enough weight to stay firmly planted on the ball. A light TW can cause exactly what you are describing as road conditions cause the weight to shift momentarily to the rear.
I would NEVER aim for the minimum TW.. Those that do are usually trying to compensate for their TVs lack of payload.