Details matter, boss

With posts every 2' it might be doable. The width of the tank is immaterial to the water-caused stress on the viewing glass, the width can be 2 feet or 2 miles or infinity - the ONLY two parameters that affect the stress are:
-- the depth of water = the height of the glass and
-- the unsupported length of the glass post-to-post, or in a fish tank sidewall-to-sidewall, taking into account whether there is bracing in between the sidewalls, that is bracing attached to the front and the back walls.
The front and back glass panels of a standard 55 gal tank of 4'x1'x1.5' have the dimensions of 4' long by 1.5' high and could be used for a tank that is 4'x20'x1.5' and the waterborne stress on the front and back 4'x1.5' glass panels would be the same.
The safety factor wouldn't be!
If you notice, in all glass thickness calculators a safety factor plays an important role, because when a 4'x1'x1.5' tanks breaks, it's a small chance of serious injury and one soggy room cleanup, but when a 4'x20'x1.5' breaks, there a LOT more rushing water and it will make any sharp piece of glass rushing in your direction a far more serious menace, plus the whole house will get flooded.
That's why I proposed extra bracing and extra-posts with only 2' unsupported glass length, not 4'.
Surely glass breaks not only due to water pressure. As I stated, poor leveling can add lots of stress, especially for such long front viewing wall. Plus a fully grown RTC will break such glass like it's a potato chip. Any furniture thrown by a fish against it is also a danger. Any nick or a deep scratch or a manufacturing imperfection is too correspondingly more, much more of a danger in a 4x20x1.5 versus 4x1x1.5.
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I am currently designing my next tank - a 5500 gal 40' x 4'-6' x 4' full acrylic but the bottom, sidewalls, and the backwall will be of 1/3" acrylic and the water pressure will be taken by plywood and posts. You can think of it as a plywood / wood plank tank with an acrylic box-welded liner. The front viewing wall will be ten 4'x4'x3/4" acrylic panels with posts every 4'...
... Similar to my 45'x4' window in the 25,000 gal koi pond glued out of five 9'x4'x3/4" acrylic panels. The latter is not filled to the top but about 10" below the top, bottom 6" is buried. Anyhow, lots of details there matter - how I glued the window together - with 1' overlaps left and right, on both sides - front and back, plus 6" reinforcement along the perimeter of each of the 5 panels, etc.
Surely, acrylic is much safer vs glass. Plus it is on the floor of my fish pavilion, not anywhere near the living quarters.
The acrylic was $2000 off CL and the glue was $2000. $4000 for a huge (ugly admittedly) acrylic window with fully acrylic posts 4' in the ground, self made and installed by hand with no heavy machinery. Versus ~$50,000 manufactured and delivered 1.5"-2" acrylic window that would be extremely pretty, one piece, much safer, etc. You pick and choose.
wednesday13
what do you think, my Sensei?
Safety factor must be considered, per above going. Yes, the water pressure on the glass will be same. The consequence of the breakage will be much, much different.