Some ideas or inspiration for larger aquarium water changes....

Hoping for some ideas on how to improve my current setup:

Please see the pictures for current process:

I have "plumbed" a water supply and outlet (some piping) from an outside tap to a point inside the house where my aquarium is. Basically this allows me to put a 50l container inside, fill it up directly from the outside tap (I also have a method to turn off and on right by the container). I treat the water there (leaving it for the day)
I then siphon directly from the aquarium using the same piping used to fill the container - directly into the garden outside. I have to watch that the water gets gets to a certain point marked on the aquarium which can be missed and cause issues.
Once the point is reached I have a pump inside of the container and I pump water using another pipe into the tank at the top of the aquarium - this is "hooked" onto the glass slider and I have had occasion where I pump water all over the dining area.
I then have to cart container etc outside and empty out any leftover water etc.

The direct plumbing from outside to inside has definitely improved things but I am looking for what other people are doing that could further improve it.

One thing I did try was putting the container outside and pumping from outside, but this took quite a lot longer with the increased head height despite the pump handling 5m. Leaving the container outside and prepping the water there would be ideal but would most likely require a really expensive pump to make it quick enough.