This is a significant improvement. It meets librivox standards. Proof listen OK.
I do have a comment and a question - which you can ignore if you so wish.
Comment - there is some noticable room echo. Is there any way you can create a deader acoustic environment?
(Such as by hanging a blanket on a wall, or over a frame near you).
Question - did you do noise reduction? If not, please experiment with mild noise reduction (perhaps 9dB). The
background noise is much reduced over your previous tests, but it is still there, and still clearly visible in Waveform (dB) display mode.
Given that you are going to spend hours recording and editing your solo book, it's worth, IMHO, a few minutes additional work to
do this noise reduction.
Well - go forth and conquer!