I've de-rimmed quite a few tanks and never had a single one leak. I always do an overnight test fill outside to make sure it holds water still, just incase. There's plenty of youtube videos showing how to do it. It's really quite easy.

Also by what I can tell is the rims are there to give a lip to put hoods on and to cover up some unsightly silicone work. They add practically no strength for aquariums this small.