Yeah, horizontal wood will be way more bendable while standing especially. You could do a lengthwise stringer then 45 begree left and right sides if your stock lengths are short. Epoxy + filler for the glue joins is plenty strong. The “Sidewinder” was an assymetrical experiment. Yeah right.
It was actually the top half of a hollow alaia and bottom with the wood going the other way. After glueing the top up I set it against the wall and glued the bottom on the table then turned to look at the finished top leaning against the wall doing a twist o flex maneuver. So I played with it for a while. No rattle though.
I know some guys do the “tounge and groove” planks but since mine is pallet wood there is no channels for me - when I join them should I biscuit or dowel them?? Or do I just glue them straight-edge to straight-edge?
If you use good epoxy you will be good. Your joins will be anywhoo. The one easy option you have is grab a circular saw, set the depth to like 1/16" and run one groove on one piece but leave the other joining piece flat. The 1/16" rip line doesn’t need to be perfectly straight. Just freehand near the center of the piece to be glued. Like a small glue pool/line. If you do that use a filler like sawdust and make a peanut butter consistency mix. Slap um together and don’t squeeze all the glue out. Many people way overclamp.