Can't you take the slip lane on the left and then go up the bottom of Sheps or even back streets through Eden Hills, or is it partly the South Rd intersection you're trying to avoid?
I don't like south rd intersection much but it's ok. Yes I thought I could do as you described.
I used to take the slip lane and the back streets up when I was studying at flinders and living in Eden hills. It's a good option with no traffic and doesn't feel like such a slog. Don't know how to avoid the south road intersection though!
When I went through Tonsley I went up Hillside drive to avoid bottom of Shpeherds hill rd, much quieter. I might try slip lane route.