I'm sure you already know this but.....the "contura" style of switch can be found at any Oz marine store like www.whitworths.com.au or a huge range of carling switches can be found here;
http://www.aquavolt.com.au/cgi/index..._id=1107141281

Also found a great water tank for the XJ on the site you listed. At least it'll suit me well, fitting neatly behind the laid back rear seats. Holds 60 litres plus the 50 in my trailer bladder.
http://www.caravansplus.com.au/catal...87000abd717cdb