The SoS was on par with EOS and HFL. Does that mean the HFL moved up a level? Yes there was no fluid promotion up, but if spaces became available, those were the leagues tjat clubs generally came from. Annan and Stranraer have both played in the SoS (first teams aswell as, recently, reserves) Peterhead, Elgin, ross county obviously from HFL, Berwick Rangers from Eos. To me that says tier 5, even with the lack of proper promotion /relegation.
EOS WIKI PAGE
The EoSFL was traditionally one of Scotland's three "senior" non-leagues which sat outside the Scottish Football League (SFL), the other two being the Highland Football League and the South of Scotland Football League (SoSFL).