So here it is, the maiden voyage of my PVC kayak cart. Managed to make it from the basement to the driveway, which was the intended usage.

I glued many of the joints, trying to keep some of them 'loose' to allow me to disassemble it and fit it in my hatch (if I ever wanted or needed to do so). Unfortunately, the loose fittings allowed too much play and the PVC shifted and caused the cart to semi-collapse on itself during use. Not good.

So I glued up the remaining joints and now it is plenty strong. No collapsing issues any more - no fitting in the hatch either (but that isn't my main concern). I have seen other creators use special pin/clips that are available at Lowes, but they were about $4 each and not worth the cost and effort to implement for my usage.

My brother showed me an example of a tiny little cart that appears to fit further back toward the point of the kayak. It was only 5"x10", which would easily fit in most hatches and was a specifically molded unit. Very neat! I am going to think about how to create one using readily available materials (Lowe's or Home Depot).