The light weight trailers only support the wheel on one side of the axle so it can’t handle as much load as the heavy duty trailer (< 70kg). If you invest in 14mm axle 20” BMX wheels they can still be very strong though. A 9mm wheel axle will typically break before the trailer bends. 10mm rear axles are usually strong enough for 70kg. There are several sizes to take various bins available from Bunnings or Stowers. They can sit inside the frame for easy removal or be fixed to the frame. The bins come with lids to keep everything dry. Works best with 16 inch wheels or 20 inch wheels.
$160 for kitset frame & hitch, $100 for new wheels or use old bike wheels
Bunnings Malloy bin 79 litre $25
Bunnings 100litre bin $35
Stower 68 litre bin $70 (better quality)
Recycle crate $10