That is how the old BroilMaster grills took care of the grease issue. The big problem I see with that solution is that if you store stuff under there and bump it or get a little too agressive moving the grill around, you might wind up with a half can of grease all over the place.
How about installing a grease container with a large spout on the bottom of it to drain it out while in place? Personally, I don't need this, as the space under the grease tray in my G II 300 isn't jam packed.