I have tried extending my Base raft (not tried others yet) and it will not allow me to extend past pretty much vanilla. I do havde s+ installed on the server but I am using vanilla build structures. I've done the ceiling and then foundation routine and can only add a single row around the normal raft foundation base before I start running into 'foundation support needed' at the corners and back.
Changed PerPlatformMaxStructuresMultiplier=1 to 2 and that didn't help either. Any suggestions would be appreciated.