Pythons definitely beat using 5 gallon buckets. To go easier, you would need the tank plumbed for water changes. Others have mentioned drains. Our mechanical uptakes are vertical pipes extending down to just off the floor. When doing a water change, we close valves and open others.
On the extreme right behind the vertical pipe is another pipe going downwards. The pipe goes under the house and to the patio. Opening up the valve drains the tank. The tall vertical pipe is from a 55 gallon tank sitting on a shelf. There are hot/cold water lines from a utility sink that fill the holding tank. After draining water, we close the drain valve and open the "fill" valve and turn the pump back on. We also have the faucet on refilling the holding tank. While theoretically, the water can gravity flow into the main tank, it's faster to pump the water back via the mechanical filtration system.
Planning something similar for the big system. Will probably just purge the Ultima II 4000s to remove water from tank and sump. No holding tank, but there are hot and cold water lines to the tank and sump, and we have an on demand water heater so should not run out of hot water. I can't think of anything else that would make our water changes any easier.