Burley Trailer Moose Rack - Obscure question

Help please! I just picked up a free Burley trailer rack which is in awesome condition. Problem is it is missing the moose rack (hence the freebie). Now I find that Burley doesn’t make them anymore and everywhere is out of stock.

Anyone know of a supplier or a way to use another rack safely. I want to be careful of the load being towed as the Burley rack looks a bit more stable than regular pannier racks.

Thanks!!