TOPIC: How much is to much

Hey guys new here. I'm working on replacing my transom and after grinding away the old glass in 2 spots where the glass seemed thinner, instantly went through hull. Set back as I need to repair both holes before I can go any further. Just want to no how much glass is to much to remove or how can I tell when to stop. For this repair I'm think of doing 1 layer chop strand mat then 3 or 4 layers of 1708. Will also repair on bottom side when hull is flipped. Any help or tips is greatly appreciated. Thanks for having me.

Boatworkstoday.com has really well done videos on the entire process.
I would start here:

Ya I pretty much had it figured how I wanted to compmete the repairs of those holes but I'm just wondering how much glass do I need to remove next to where the stringer channels are do I remove as much as I did around bottom of transom so it's clear or can I just rough it up and glass over top. Thanks in advance