Rattly if there’s not much in there – rattle from the rear wheel bouncing and (I think) the hitch, rather than its overall construction if that makes sense – it’s pretty solid otherwise.
Any reason for the QR rear end? Having ridden with mine fairly well loaded, I’d be looking to get as much stiffness in the overall chassis as possible – there’s a fair bit of twist going on and a bolt-thru rear end is stiffer.
In terms of spares on the road, unless you’re going for a proper old fashioned 135mm QR back end, you’ll easier find 148x12mm replacement wheels/hubs IMO in Europe, and the performance benefits will be well worth it.