Magni's standard approach has been as Brett states: fiberglass cowl over steel frame. A monocoque design that took full advantage of the potential weight savings would, in fact, be lighter, especially if built from graphite fiber instead of glass. As Buck states, a proper monocoque cabin having the same layout as a frame-plus-cowl cabin would contribute somewhat less to HTL.
As with the rotor mass, though, we're dealing with rather small percentages of gross, so the helpful effect of monocoque, while real, is apt to be modest.
Going way back to 1969, Jukka Tervamaki admitted to the inefficiency of his own frame-plus-cowl construction when he introduced the ATE-3, ancestor of the Magni line.
Another contributor to HTL in these aircraft is the fact that the Rotax 900-series engines use a gearbox-up configuration. This places all of the engine's mass below the prop thrustline.
Obviously, there's a certain amount of speculation here. Whether the HTL offset is 8, 10, or 12 inches can't be determined from the pictures. But it is almost certainly in that range. If we knew the dimensions of the h-stab, we could estimate its lift at various speeds and angles of attack. That would be a good start toward determining if this craft is capable of PPO.