I see what you mean but the tube I would get is like 60 ft. And cant leave the door open. Like if the water is coming out in a rate of 2 gallons per hour then there is barely water running through the tube. Then when the tank fills up, there is 60ft worth of water in the tube. Plus its not only 20ft it would be 60ft.If you have 60 psi water pressure (typical) and the tube is 1/4" OD (~1/8" ID), pushing the water at a rate of 2 gph up 20 ft is not a problem. It will be an inconvenience for a day to have the tubing running through the house, but you will have no issue slowing down the water production. Just tell everyone in the house "Don't touch the tube!!" and use a clamp to hold it in the tank (or it will inevitably flip out of the tank).
For emptying I would get that Sicce micra plus pump and some 1/2" vinyl tubing. Run it to the nearest drain (bathroom, kitchen, etc) will take about 20 min to empty the tank.
So much easier than buckets... and so much less of a mess!