Indoor project?

I've been pondering the options for an indoor G scale layout for a few days, largely inspired by my bash of the Liliput diesel shunter and the Zillertalbahn prototype...

What? Remember my Roll-wagen project? Yes? Well imagine an indoor layout with a standard gauge interchange point. I'd need a new roll-wagen with the ability to load and un-load standard gauge (Gauge 3) wagons.

Here are my initial sketches and some inspiration, and to follow some prototype Austrian track plans.