I'm going to install them and have already bought the split charge relay :-
1 Is it really necessary to buy a twin battery tray or can I simply use the existing fittings to hold the new batteries down2 Do I really have to fork out for Optimas or similar when I do not want to run a winch and all I really want is to be able to use my Engel Fridge (or similar current consumption) on the deep cycle one