I used to do these full moon double exposures with my 35mm film SLR .. where you marked the film with a line across it and the 'rails' before closing the back .. then SHOT the moon (taking notes on placement) .. .. then wound the film back (leaving a tab available) .. and re-inserted the film .. aligning the mark on the rails as best as possible :o) .. and then shot your foreground subjects (day or night)
I had a hard time keeping the moon in the viewfinder at 600mm .. always cranking my tripod knobs down tight .. checking the placement .. uncranking my knobs .. re-aligning