I would like to do this as well! I'm a little concerned about the structural integrity, though. Does your tank seem stable? What would you do differently for the next time you de-rim?
i de-rimmed a 5.5 gallon as well, only the top rim. my tank is plenty stable. as for what i would do differently, i would have started with the inside. i started by trying to pry from the outside, and broke a couple of razor blades (!!!) in the process. the inside is where the silicone is, flip it upside-down and cut the silicone you see. after all the silicone in the inside is cut, go around the outside.
i did, however, notice that the glass underneath the rim wasn't very smooth, like they didn't bother to sand it because it was going to be covered.
next time, i think i'll get some glass sanding paper to remove the rough edges/excess silicone. i still have the rough edges on my tank.