Our habits have to change eventually. Getting stuff to go in a cardboard or styrofoam cup or box is no longer a good idea. One solution might be a modern Oryoki set, containing 3 nestled bowls, a plate and cutlery consisting of fork, knife and spoon. This set should be very lightweight, durable and easy to clean and carry/pack.
Plate: because you can’t cut vegetables or meat in a bowl
Large Bowl: rice or pasta
Medium Bowl: salad, veggies or soup
Small Bowl: Tea or coffee (or Sake)
Here is a photo of an American ceramic Oryoki set. The traditional Japanese bowls are made of lacquered wood. I am not sure what material would be best for a modern set.
I carry a set of cuttlery with me when we are touring, because we have a lot of catered meals and sometimes those are served with plastic utensils. Here is a picture of the cutlery I carry with me:
You can click on each of the photos to go to the web page of the dealer/manufacturer.
I imagine the plate could be a top that fits on the largest bowl. When placed on the large bowl it would keep the rice or other food warm, and when turned over it would become a plate.