My 1.8kg Quechua T2 Ultralight pro is described somewhat creatively as a two-person tent. I was comfortable in it, and my bedding took up two-thirds of the space inside. I could fair go another foot on the length, though. The porch is a decent size and has room for my big Arkel panniers and Inertia Designs seat bag, plus my water bladder, cooking kit and so on. But cooking inside is a non-starter.
My ultralight approach means my groundsheet is half of a thin (bread bag thin) polythene dustsheet from the DIY store. It worked a treat, and will probably last another trip.