I would go for the “flood” beam pattern if it is for reverse lights. No point in being able to see far back (spot pattern) if you are going to go hit something close by when reversing eh?
I`ve got a couple of 18W LED driving lights in my Discovery. Something similar would work well as reverse lights as well:
http://forum.autolanka.com/topic/14308-land-rover-discovery-1/page-3?hl=+land%20+rover%20+discovery
Another option would be a 12v LED work light, a single 27W light like this would do the job: http://www.diytrade.com/china/pd/9629680/27W_Square_LED_Work_Lamp_Off_road_atv_lights_12v_24v_auto_work_light_led.html