I think I'd start by making friends with an engineer or a kid who gets A's in physics, just to get an idea of the loads that you'll be dealing with at full depth. Red oak, plywoods, southern yellow pine, they all have known structural properties that should be looked at along with the holding properties of the adhesives and fasteners used. Depending on how you frame it you'll have all sorts of compounding forces at work on the materials. Shear, compression and tension, dynamic and static loads, all limited by the strength of the weakest link.
Anything is possible as long as you know what the forces and loads are that you have to contain.
As for potentially catastrophic failures...
My son tossed a little plastic toy that hit our 30g. when he was just old enough to sit up on his own. Must have hit it just right 'cuz we were swimmin' in fish that night. 30 gallons of water can make a heck of a mess in the living room. I don't even want to think about 400.