I have a John Taylor outdoor cover and take it when away for overnight parking. Bought when I had trads and works on the Plus Four. A good cover that does the bonnet and cockpit and just goes over the top of the spare wheel. I also have an old-ish Librands short cockpit cover. It's lost it's waterproof layer but still handy to pop over instead of putting the hood up. I intend re-proofing it .
My Librands luggage rack with sidescreen storage for a car with spare wheel was fitted when buying the car new a year ago.
I've just bought leather luggage straps from a Miscellany ad. Using them in a couple of weeks. Until now I've use ratchet straps, mini versions not the big ones. Also a large waterproof bag to put over a case on the rack. Bought from ebay. Used earlier this year and gives good waterproofing.
I have the Cobra's head high brake light and have made an LED plug in extra one for when the suitcase is on as it obscures the brake light. Quick and easy swop using Superseal connector plugs.