Firstly, my advice would be, try to do smaller water changes more often. Second, I would try to find a way to not need to change as much water as often. The primary reasons you NEED to change water (Thor can correct me if I am missing something), is to remove nitrates, to remove phosphates, and to replenish other (trace) minerals.
There are a number of ways to remove/reduce nitrates & phosphates. One is plants. Those are two of the three primary nutrients in ALL fertilizers, aquatic, home, agricultural and otherwise. I have started my first true moderately/heavily planted aquarium, and even though it is moderately stocked with fish and they are well to overfed, I have actually had to buy bottles of nitrogen and phosphorus to add to the aquarium. They eat that stuff up. My 65, I can't do enough to get rid of the stuff, this one, I am trying to add it.
You can also add media to your filtration. SeaChem Purigen is awesome at removing nitrates, and helps with phosphates. They sell other media specifically aimed at removing both, you could look into them of they become a problem, but I'd make sure to test first. Just reducing them marginally could reduce the amount you actually need to change.
As far as trace minerals, there are various supplements you can use, And you don't really need much of any of them.
The python vacuums all work well. Never tried a 50ft version, but they have pump primed, battery powered I think, etc. They are quality products.
Thor, using the canister to do a water change is so damn genius I am embarrassed to admit I never even thought of that.
