A more practical hint: You can acquire very smooth board already coated with an adhesive layer from certain outfits like Oregon Lamination.
But after you peel off the masking sheet, putting down a large print is still going to be relatively tricky without an appropriate roller-feed machine. It's analogous to laying down Formica. No need a big slip sheet of silicone release paper, but a good pressure roller. Practice, practice,
practice... and then, right at the brink of insanity, you'll purchase a machine.