Rubit was 8 of 12 from the field for 18 points and 9 rebounds. Ammons had 17 points and 9 rebounds. Ken Williams contributed 13 points, hitting 3 of 5 3-pointers.
Rubit now has a total of 971 career rebounds, ranking second all-time in the Sun Belt Conference.
South Alabama (5-3) got off to a fast start and never slowed. The Jaguars led 12-3 at the 15:26 mark. They went on a 15-0 run to push the lead to 29-9 with 7:21 remaining and led 44-23 at the half.
The Jaguars outshot Spring Hill (0-6) from the floor, 50 percent to 30.6 percent and controlled the boards, pulling down 55 rebounds compared to 24 for Spring Hill.
Frederick Gatson led Spring Hill with 8 points.