I want to see what you do with the sump.
Props for taking your time on your de-rim. I only have done the tops on my 20 longs and that alone takes me hours. I see many people leaving the excess silicone on. I feel like I did a good job on both mine but still managed to scratch them up very slightly, yours looks really good. I will likely never de-rim a tank because the side silicone looks bad but I just like seeing it done well.
Please post updates as you go.