A Mammoth Clansman at the peak of the Body Stage transforms into their respective Pranic Beast form. At the same level, a Free Human takes on their Human Avatar form. A Cooter Clansman had their Spirit Weapon transformation.
Their body transforms into an object, behaving like a Spirit Weapon. Its shape and size resemble a Cooter Clansman's heart, continuously pumping out Prana. Surrounding it to form a false body would be mist influenced by their Primary Nature.
This false body could either be the same size as their original body or could grow into a giant. The only difference would be the Prana consumption necessary to maintain such a giant false body.
The biggest advantage of this is the fact that the false body is merely a mass of fluid acting as a Spirit Weapon. Whether or not it gets obliterated wouldn't affect the Cooter Clansman. They only need to consume more Prana to regenerate it, like a slime.