I don't think there would be enough pressure at bottom to spread side and end glass in typical 5 gal
tank, about 15 psi. But why risk it?
Main problem with de-rimming bottom is glass will rest on supporting surface, smallest piece of hard grit will cause unequal pressure and could break bottom glass.. You'd need some kind of pad under tank or an elevating "rim" on bottom. Ideally you'd want the bottom rim to extend up sides just to keep every thing in position. You're right back where you started. In the days of angle iron framed tanks, the bottom frame sat inside a slightly larger inverted angle iron frame that was top of the stand. Now you're really back where you started.
Why for you wanta remove rims? I don't like seeing water surface line thru glass, I have often widened the top rim, in various ways, so I don't have to fill tank so perilously close to top. Bottom rim, besides elevating glass, can hide some seriously ugly, but benificial, gunk at very bottom of gravel