Another option is buying an Android tablet and using an app such as Miracast receiver to make it into a wireless display. You could also do the same with a Windows 10 tablet as that has the ability to use it as a Miracast display built into the OS.
A tablet has its own battery so isn't draining your laptop and when your not using it as a display you can use for other things such as watching videos, browsing the internet etc.
A 14 inch tablet can be quite expensive, but you can get brand new Lenovo or Huawei tablets for around £100 if a 10 inch screen is big enough for your needs.