Hmm.
There should be some chunks out there that are pretty dark, covered in frozen organic goo, and pretty big.
Warming them would make them brighter and more visible, plus give use of the organic substances on the surfacee.
Not certain there'd be anything roughly Mercury sized out there, but there should be enough icy aggregates out there to be able to tow some together and make your own world.
Exactly!
With a world full of resources. Even moon sized planetoids would have incredible amounts of area. Out that far, they would also have volatile gases not present on our Moon.