There are also some smaller "dwarf" gopher snakes* being captive bred. We had lots of gopher snakes in So. Calif. when I lived there, they are nature's best mouse-traps& very intelligent & cool serpents...active by day (unless too hot). And you're right, not quite as big or heavy-bodied as bull snakes...I've had both (& raised both).
*for example: https://www.nps.gov/chis/learn/nature/gopher-snake.htm