Have a look at Front Runner, http://www.frontrunner.co.za , who are very experienced in supplying (contact them for UK outlets) and if in SA fitting expedition equipment. They do a rear fender mounted fuel tank. As for the fridge they also manufacture a fridge slider which is fitted above a Wolf Pack Slider (4 wolf packs) mounted in the rear of your vehicle with access through the rear door. We travelled from SA to the UK using their Roof Rack and aforementioned equipment without any problems. Further advise, only carry what is needed as most of the equipment you think you will need is never used and uses unnecessary space and only adds on extra weight (be as light as possible). Unless you really go into the sticks, most of the roads in Namibia, Botswana and SA are generally in fair to good condition and we never had need for any special protection equipment, under body, roll cages, etc., simple don't get yourself into situations you can't get out of. Hope this helps.
