MattCrouch wrote:
Glue the joint with liquid nails and then glue a 1/4" piece on top and bottom of the 3/4" that is now glued together. Do you think that will provide enough support for my wife and I?
As someone else pointed out - and as a woodworker, there are much better glues. I too like the Titebond's. Titebond III is (for all intents and purposes) waterproof.
I'm not sure about the support structure but I wouldn't put that much weight on any sheet of plywood spanning that distance without supports.
I'm doing a bunk bed for my 150# son and the bed is 3/4" plywood and 74x36". If I can elegantly create some cross supports for it, I'll do so. If I can't then the fallback approach will be something based on the notion of a torsion box.
A master craftsman, David J. Marks, and host of the TV show WoodWorks aired an episode on torsion box construction. (https://vimeo.com/5082731) Very strong for the weight.