I always carry a full tank, never know for sure what you’re getting into. Things like 3 days worth of firewood, 4 bikes (that might not be used), 2 kayaks those things bug me just a little.
If 400lb was an issue for me I would have issues to fix. My fresh water is right above my axles and the lowest place on the trailer, the perfect placement of weight. I even believe the correct placement of weight helps in trailering(makes me feel good).
In my trailers I have done over 80,000mls in two trailers with no issues.
All this said you need to know your own equipment, how it’s built and how it’s wearing.
Just my experience/opinion