Nordkyn makes a nice, light, non-bungee belt they call a hiker's belt that has some d-rings on it, so you can use basically any leash - if you don't have double ended leashes, just get an extra clip from the hardware store for the loop end or use a carabiner.
My favorite double ended leash is Karma Collar's. It has a fixed o-ring in the middle, but you can also add any number of floating o-rings you like on either side of the fixed one. They are leather, but I use them in all sorts of weather and they hold up beautifully.