When I wake up from a very late morning LD (after sleeping all night) and prepare myself for DEILD, I just feel very uncomfortable and am unable to get back to sleep.
Is there any way to surpass this, or is it just impossible to DEILD at the point where my body is telling me “get up, asshole!”
It’s not impossible, but its just gonna be kinda difficult since your internal clock has run its sleeping course. If you simply cannot do the DEILD cos you don’t feel comfortable then just switch to a comfortable position and go for a WILD, which is sort of the same thing haha. You could try using auto suggestion, to help you wake up randomly throughout the night to attempt DEILD.
Hopefully I helped in some way 
Best of luck ~