After buying my fuoco it quickly became clear how bad the original seat is. One of the main problems for anybody over 5'6" is that the seat base has a rise between the driver and passenger bits so there is more room in the pet carrier.
I've used a seat from a Aprillia Habana which I've modified slightly so it sits in the pet carrier rather than on it. At the moment the seat is sitting on a block of polystyrene while I work out the optimum height, but I think that its an interesting avenue of investigation for anybody who really wants a good riding position for driver only riding.
I don't normally ride with a pillion so I don't have to worry about that. And I have a Shoei XL size helmet which doesn't fit in the pet carrier anyway so I'm not too bothered about that.
What it does let me do is sit much further back than on the bike than would be allowed with the normal seat, or any seat using the normal base...
I'm still working on the best solution, I think that I'll ditch the base of the Habana seat and use a flat plywood one, as I can feel ridges in the base through my rear.
The other thing I had to do was drill a small hole in the pet carrier to let any rain water out of the bottom, otherwise it will collect in the pet carrier.
I realise its not a perfect solution for everbody, but it works for me!