What width of tiller is that? I'm running a RS1400 (53" cut) that was originally sold with YM2000, on my YM186D (YM15010D). This is a little larger than the tractor wants. I installed the rear 'training wheels' to limit the depth of cut and prevent occasionally stalling. Does yours need this? Also, I don't clear the grass before tilling. How much difference does that make? Great photos!
I usually try and spray with glyphosate a couple of times before I work the ground.
Have you read the latest health dangers about glyphosate? Farmers are abandoning that chemical like the plague. In some parts of the country it's been band in certain counties.
I probably know more about glyphosate than anyone on this forum and work closely with the EPA in the regulation and safety of pesticides.