That’s -65dB after mastering, right? You may find that the mastering tools can help your noise way more than you think. Many home microphones naturally produce a low-pitched rumble sound that can mess up noise readings. Low Rolloff sucks that rumble right out of your performance. It’s one of the reasons you must apply the three mastering tools in order.
This is where actual audio editing comes into the picture. Most of the time you should try to suppress mouth noises, tongue ticks, mistakes etc. You can cover them up with the Room Tone segment you captured along with your live reading.
The process is not Copy and Paste. You can use Punch instead.
https://forum.audacityteam.org/t/punch-copy-paste/28906/1
Punch was designed to be a gift from the angels. Drag-select an error in the performance. Punch. Punch will tailor the replacement sound so it exactly fits the selection covering up the error. Under certain conditions Punch can form a gentle fade on both ends of the correction so to be as unobtrusive as possible.
I’ve never used it. Let us know how it goes.
Koz