LTC4366-2 ISSUE

Picture:  input  from 160V ->350V/2s->160V; output is 160V->200V/2S->160V;  (because the input range of the latter power module is 100V to 200V)

ISSUE:  when input was 350V,and output is 200V,the MOS is  worked in variable resistance region。NOW, the Vdg is 138V,  Will MOS be broken down?   

I think the mos will be broken down, so  what better circut do you have  to withstand 350V/2S?