This is a very good write-up.
If I could add, the best way to waterproof an esk8 is actually to ride it in the rain.
It will fail. When it does, you fix it so it won’t fail that specific way again.
Repeat that process about 42 times.
Now you have a mostly waterproof esk8. Except changing motor bearings sucks.
And you’ve replaced every single part of your esk8, possibly more than once. But now it’s waterproof. Mostly. Each time you repeat that, it takes longer to fail again…