Hey, thanks for writing such a detailed post 
It’s interesting to hear how you’re approaching everything 
10 days/level will take you 1.5 years to reach level 60, which is significantly better than your goal! ^^ Usually for a 2 year goal, doing around 10 lessons a day will get you there. So you still have a leeway to reduce lessons a bit if you feel overwhelmed at any moment. Remember that consistency is key. Sometimes it’s better to reduce the load if that will make you more consistent with Wanikani.
Any plans on how you’ll approach both reading and grammar? For reading, I’d definitely suggest the book clubs here on the forums. These days, there’s so many book clubs around and the it’s easier to find something of one’s taste, and the help that 先輩 leads to tremendous improvement. I admir that I should participate on them myself 