Chris,
Excellent question. My recommendation would be to keep both, depending on your situation in the time of need, the safety line can be easy to grab & pull yourself to the stern ladder.
If you are racing, the stern safety line must be in place per Class rules.
You can also use a good quality carbiner & plastic ball on the port side of the safety line and then unclip it from the port ring if needed …. the ball will not fit between the rudder & transom and effectively increase the length of the safety line.
Loop your safety line to the rear of the ladder.