Cheers for the reply Jason.
I only started thinking about it yesterday so still trying to find out what's in the art of the possible.
Thanks for the advice on the water tank and spare. I can't find the water tank I'd seen now I've started looking properly for it. It was essentially wheel shaped and fitted where the spare does, using the bracket to secure it. The benefit for me being that I can drop it and fill it rather that drilling a big hole in the side for an inlet.
I spoke to Matt at VWT5Upgrades who said the electric tailgate will not lift a bike rack with bikes on and William at Wheeliams who reckons it won't lift his tyre carrier whilst its loaded.
I can definitely upgrade the struts but not sure this will be enough, I'll do a bit more digging.