Ubuntu image without Clonezilla

Hello !

I would like to install Ubuntu on my LattePanda 4GB as well as Windows 10 in a dual boot configuration.
I first tried to follow this tutorial https://www.lattepanda.com/forum/topic/313164 and https://www.lattepanda.com/forum/topic/312430
I worked pretty well, but I noticed that the 7" display from LattePanda wouldn't work, when it worked very well on Windows.

So I used the image given on the official documentation https://docs.lattepanda.com/content/1st_edition/os/ and the 7" display started working, but I had to wipe Windows from the eMMC during the installation, because of Clonezilla.

I tried using Clonezilla to create a dual boot, or installing Ubuntu on a USB drive, without success.
So my request is : 
Having an LattePanda customized image (with 7" DSI display support) without Clonezilla, so I could install it in a dual boot configuation
Or a way to use the image given in the LattePanda official docs (with Clonezilla) to create a dual boot.

Thank you by advance for your help !