Having spent a lot of time doing water changes on multiple tanks, and spilling a lot of water on both myself and the carpet, the 10L containers I use (segregated/labelled for waste or clean water) are these:-
https://www.amazon.co.uk/h32-Litre-Plastic-Container-Approved/dp/B00TFVJM36/ref=sr_1_2?ie=UTF8&qid=1531037940&sr=8-2&keywords=10+litre+plastic+containerThey are slightly larger than 10L, so for the clean water containers I measures out 10L into the container & marked the side to make it easier to add the appropriate amount of dechlorinator.
As for refilling the tank with a submersible pump, this is similar to what I do with my largest tanks, using the external filter, which has a port for this sort of thing. It makes water changes so much easier.
I guess if you get a large plastic stack box to hold the pump that could work. It doesn't have to be large enough to hold all of the clean water as you can add to the container while the pump is working.
The only thing I would point out is get a pump that is strong enough to pump the water to the top of the tank, and not so strong as to blow all of your fish out of the tank.
I'm using a pump (that can be used submersed or dry) to power the manifold in my river tank, so all I can say is that you really don't want one that powerful -
https://www.amazon.co.uk/Jebao-Jecod-DCT-12000-Speed-12000/dp/B00SWUWV5C but they do smaller ones, as do other manufacturers.