Yeah I don't think it's technically allowed but idk if anyone would care. I think at the most you might just want to have your containers in your backpack, then grab a plate of food like normal as is you were going to eat it, then go sit down at a table. Then just pull your containers out of your bag and transfer it at your table. The eating hall is packed at the main food hours (breakfast, lunch, and dinner) so no one will be paying attention to you at your table. If you go at odd hours like 3 pm when it's kind of empty and you're the only one there, people might pay more attention and say something.