Not sure what rules apply to your flight but 400 lbs is less than 30 minutes at low altitudes and that would be the absolute minimum for me provided VMC, two runways. etc.
To arrive at an airfield with only one runway with less then 30 minutes of fuel remaining is not a good idea in my opinion.
I would say plan on landing with at least 30 minutes and plan for an alternate if your destination only has a single runway.
But most importantly: follow the applicable rules and regs.