I wouldn't de-rim that tank. Too much length on the front. It would definitely bow out, and hopefully not too much. If the glass was 1/2"... then I'd think about it, but I'm pretty sure it wouldn't be.
I used eco-complete in my old tank. I didn't have C02... but, ime as we as I've heard from others (in my substrate searches) that eco-complete has a tendency to hold BBA spores. I also found it impossible to clean from hair algae too. I'd try to suck the hair algae out, and massive clumps of eco-complete would get sucked out too, cause it's all bound in it.
Saf T Sorb is a cat litter. Not gonna find it at Home depot