Oh, I dunno. If its orbit is currently stable, then all you'd need to do is increase its velocity, whenever you add mass.

It might be a good object to seed with lunar landfill.

I'm thinking it could be like the outer space version of Sealand.

https://en.wikipedia.org/wiki/Principality_of_Sealand

https://en.wikipedia.org/wiki/HM_Fort_Roughs