Theres no reason why you would not be able to mine a ringworld w/o any fancy matter to energy converters. After all if you build a ringworld in a system with planets it says those planets are deconstructed to be used in the construction of the ringworld but it doesnt make it cheaper or anything based on the amount of planets in the system. So you still have all those minerals on the Ring.

Ascendancy Ringworlds is supposed to allow you to build Ascension Perk Ringworlds.
It wasnt planned to be some complex thing that made sweeping changes introducing new districts and jobs that set them more apart from their vanilla counterparts.

I might do such a thing at a later date

...maybe have some fluff like a massive matter-to-energy converter that then needs to be mined out before it can be activated again?