Hi,
Each and every time I need to use the extroot feature, I always forget something and it never goes well from the first time. So, I planned for some time to make it automatic, and yesterday it was time to do it

So, this project delivers a ready made .bin firmware for TP-Link MR3020 (or the command line to build it yourself for a different router) and a script to make it easy to build the extroot filesystem.

Two commands and two reboots is all it takes and it works every time.
All you need is the router itself and a USB memory stick dedicated for this (during the process it is repartitioned and formatted).

https://yunofun.wordpress.com/easy-extroot/

Enjoy!