Probably "oversharing" but.... whatever.
Old,and usually very cheap aluminum disc sander plate. Can be modified with a hand drill(stepped Christmas tree bit) although a drill press makes it easy peasy. Other than drilling,all std 7/8-14 hardware makes this entirely doable in a home shop.
Lay out hole spacing with any cast ribs underneath,taken into account. Also there can be a raised lip under there as well. To say how durn convenient this is well,would be a gross understatement.
Good luck with your loading.
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