Since you are adding a drain, you will also want to add fill line that is able to mix warm/cold water to a desired temp.

Same type of deal, attach hoses to drain and to fill.
So you can leave the hoses on perhaps all the time and use a valve to switch between normal operation and water changing.

One valve to drain, one to fill.

Tell the wife it'll save you lots of time/energy to spend with her more, less work and less mess.

It's all true also.

Regards,
Tom Barr