How would I go about setting up an Indesign document for the precise dimensions of 4' x 8'?
Should I create the document at the exact size?
Would Illustrator be a preferred option instead? If so, is there a specific way to set up the Illustrator document for a 4' x 8' output?
I personally would use Illustrator for large signage. Just make the artboard the desired dimensions. If there are elements that bleed, make sure to inquire with whomever is doing the printing how large they want the bleed to be set up.
Same with ID if you choose to use it.