Does anyone have any great suggestions regarding securing these pumps well enough to stay in place when the yak is tipped to plug-in the wheels — ideally, a place that's out of the way, yet handy enough to grab from the seat when needed?
How about right where you might use it? All of our 8" hatches have a pair of small holes in the inner lip. They are designed for attaching items. Shown here is a "boombat" for the sail. I usually also keep an emergency tow line attached here for quick access. The attachment lines shown are left over Spectra scraps.
As an alternative, you can get some industrial grade Velcro, glue/screw/2 way tape 2 strips to a convenient location and wrap them around your pump barrel for quick release.