I've succeeded using Sheet-to-Tiller Self-Steering in the past (seventies and eighties) in a 23 feet sailboat on any wind angle.
Learned a lot from the book SELF-STEERING FOR SAILING CRAFT by John Letcher.
As Randy says, I also found that surgical rubber tubing is the better spring material but get plenty of these rubber springs because thay are fast degrading with direct sun light.
boat is an old IOR one tonner (39 feet) with tiller helm
. She is a dream to sail. I think I'll try Sheet-to-Tiller Self-Steering again and check if it's a doable concept
in a 10 ton boat.