To douse the tobacco fields with moonshine undetected in The Fine Joys of Tobacco for Hosea in Red Dead Redemption 2 go up to the first two field and pour moonshine. Sneak north to the track between fields and go across to the next field when the guard is walking the other way.

Wait for the guard to head west and cross to the next tobacco field to douse the tobacco fields with moonshine undetected in The Fine Joys of Tobacco for Hosea in Red Dead Redemption 2
Douse the tobacco field. Go west until you reach another track and wait for the guard to walk south and sneak across to the next field.

Wait for the guard to head south and cross to the next tobacco field to douse the tobacco fields with moonshine undetected in The Fine Joys of Tobacco for Hosea in Red Dead Redemption 2
Douse the two tobacco fields with moonshine. Head back south until you get to another track between fields and wait for the guard to walk past and sneak across behind the guard.

Wait for the guard to look west and cross to the next tobacco field to douse the tobacco fields with moonshine undetected in The Fine Joys of Tobacco for Hosea in Red Dead Redemption 2
Douse the final two tobacco fields with moonshine.