Yeah the difference isn't too big - but with your bracing I'm sure that will also add to the overall strength of it.
The tank looks very well braced and if you're patient with a steady hand I'm sure you could trim down the silicone with a razor blade or a craft knife, just be very careful not to scratch the glass. If of course it bothers you - if not, just leave it.
If the tank was mine, I would have filled it and had it running anyway solely due to impatience :sml2:
The conflicting opinions on the internetz about laminated glass I've found in the last half hour has just confused me even more. Some say it's stronger, some say it's weaker, some say it's no different. :dunno: