I mean, I have a 10 gallon and I'm right next to the bathroom, but I use a 5 gallon bucket :P I usually only do 50% changes if that, usually between 25 and 50%. Just use a gravel hose. And since I can't carry that to the bathroom without it spilling I scoop out like 2 gallons worth of water with a 1 gallon fishbowl and dump them out and then I take the bucket in.
Same deal for filling it. I fill the bucket up, leave it in the bathtub until I've put about 2 gallons in the tank using the bowl, and then I bring the bucket in.
It's not that hard at all. When I do a 100% (Which is only after an ill fishy) I just empty most of the water into the bucket, dump it once it's reached 5 gallons, repeat, then I take the gravel out, and carry the tank which has a tiny bit of water left into the bathroom and I clean and stuff in there, then move the tank back to my room, add the rinsed gravel, and then fill it up all the way using the bucket.