So I checked that for you.
A330-300 when empty is just on forward limit. Fuel moves you a bit more FWD and above 35 tons it moves trim to AFT. So index on TOW is ok but on you may have problems on ZFW.
And as I said PAX and cargo really depends what you have. If you have more specific question feel free to ask.
I was curious about mentioned 747-400. I tried that and full of PAX, no load, it was well within limits. I would say it is configuration problem.
I check documents for A350-1000 and few flights for A350-900. As empty is it hopeless. No way it can fly without some weight in the aft. It is quite fine for normal flights, nose heavy but fine. Passengers do a lot in the aft and cargo too if you have any. I would say it is because that aircraft is so long. For TOW limit fuel helps you if you have up to 48 tons. Fuel up to 66 tons makes no change to trim and everything above makes everything horrible. For long flights you end up in a corner of envelope for MTOW and FWD trim index.
If you need some examples or so let me know. I will make you flight with your numbers.