There are no special requirements with regard to regulators for light-weight and kayak diving. Although 1st stage port arrangement can make a difference if diving on side mounted cylinders. when diving with this configuration is it's better if you can route a long contense gauge hose from the first stage straight down and back up the side of the cylinder, secured in place by shock cord looped, tent rubbers or inner tube loops around the cylinder, with the second stage hose routed in such a way that it lies close to the chest but allows full freedom of movement when in use. This keeps hoses tidy and out of the way.