Finally, perfect first raft layer (from Cura)

It's taken a lot of fussing with this, but I think I've finally dialed things in for the raft.

Cura 2.3.1
(Visit Settings and select all checkboxes so that you can see the options in the main screen.)
Custom slicing options:
Build Plate Adhesion:
Type: Raft
Raft Extra Margin: 6
Raft Air Gap: 0.2
Raft Top Layer Thickness: 0.2
Raft Middle Layer Thickness: 0.3
Raft Middle Line Width: 0.8
Raft Base Thickness: 0.3
Raft Base Line Width: 1
Raft Line Spacing: 3
Raft Middle Print Speed: 10.0
Raft Base Print Speed: 5.0

I also tweaked the OctoPrint startup GCODE right at the end. Someone suggested that after the priming line is printed there might be a retraction of the filament which then needs to be re-primed before actually starting the sliced GCODE.

Code:

; pause a second
G4 S1
; start slightly extruding to re-prime
G1 E0.2

Ultimately, this appears to produce a reasonable first layer. I still have a slight issue with that initial rectangle sometimes not adhering in a corner but I'll work on that next. (If I hold down the offending corner with Count Spatula until some internal lines are laid down, it works out for now.)