Hello,
Configuration of a California is a lot on personal choice, wishes and needs.
For example the heated windscreen. If I would in a position to get a new California I would certainly add this to it (especially it is not that expensive). Yes, the parking heater can clear the screen, but it will take a while. My camper is my daily drive and there were situations that I desperately would have needed the heated windscreen.
About the additional seat. We got one with the California too. Yes, the seat is removable, but it is so heavy that it is very difficult to get it in and out easily. Our seat was put in the camper at the dealer when we collected the van, than I took it out and now it is in the garage (for almost 4 years now).
Trailer hitch is handy. I would never go with the original bicycle holder again. It looks good, but it is not practical. I certainly would prefer to get a bicycle holder sitting on a trailer hitch. It is so much easier. If you plan to carry bicycles maybe you want to consider it.
I don't know if the digital cockpit is part of the Ocean in UK or not (many of your items on the list are standard in the Ocean here in Ireland). I certainly would go for the digital cockpit. It is not necessary, but it looks brilliant. And like the heated windscreen it is not that much more. Also I believe it will add value to the van if you ever plan to sell it.
You might want to consider to change the tyres. I good rid of the original Goodyear tyres. I thought they were terrible. Very often I had the spinning front wheels. I changed after 17k km to Michelin CrossClimate and it improved a lot.
Exiting times. I can imagine that while you are waiting for the new camper you will start to look for accessories. They are endless for the California. Enjoy the research and the new camper.
Happy California,
Eberhard