Has anyone given any thought to the other worlds in the Ghenrek system? I'm thinking maybe a sword & planet approach. Taking account of the rather icy nature of Ghenrek IV, I'm thinking anything further out would likely be frozen, but that gives 3 planets to play with. Some ideas:
Ghenrek III: Cool, Dry - A decadent, desert Martian/Barsoom world of dying civilisations and airships, possibly under Markab influence. Lighter gravity.
Ghenrek II: Warm, Lush - A tropical, Venusian world of giant lizards and savage tribes, both reptilian and human. Dinosaurs!
Ghenrek: I: Hot, Tidally Locked - The Day side is burning hot, the Night side is mostly cold, with eternal ice at the night-pole, but broken by vulcanism from the star's strong gravitational field. A very Elemental feel. Civilisation exists in the twilight zone.
Another, related possibility is to use the old Judges Guild 'Portals' worlds like Torsh as the basis for developing the Wilderlands' solar system?