I've decided to sheath the bottom panels in glass cloth and epoxy to provide a little more strength, stiffness and impact resistance to the thin 4mm ply hull panels.
I chose a 200g fine weave cloth (because I found some 130cm wide that will cover the whole bottom panel in one width.
I draped the cloth over the hull, then spent 30 mins or so carefully smoothing it out by hand. It's amazing how easily it conformed to the compound curves of the hull. I ran a strip of packaging tape just below the chine and will trim the cloth back to this once epoxied, then fill the joint to blend it into the topside panels.
I'm going to leave it draped overnight and get some more help in the morning to epoxy it