Looks like you've had lots of fun
I'm talking about making 3 sections "cross-wise" rather than "length-wise" like you did. It wouldn't be quite as convenient as a hatch, but I think it would be simpler and sturdier. The concept is sort of like a hard panel-type tonneau vs a hatch-type one.
Apologies for the crudeness of the sketch, but here's the basic concept (attached).