So in fitting the front winch I have been looking for a location for the second battery. Playing around with a battery showed that there is not really enough space under the bonnet. The problem is height rather than length. Anyway, the rear tray in the boot is an attractive location for the battery and it puts more weight over the rear wheels.
My car was converted to take a rear winch and this was fitted in the rear tray with a hole for the cable exit. This was letting water in now that the winch is not fitted so in order to fit the battery I needed to fill the hole.......