Nitro it doesn’t sound like you’ve made it very deep into the planning process yet. What goals are you trying to achieve? I think a lightbar is already going to have plenty of spill. Normally they are constructed as a repeating pattern, no LEDs at different angles on the side or anything. It seems that arrays of TIR optics are often employed. Maybe you should pickup some offroad magazines and look at what’s already out there?
Also, here’s FlashPilot’s thread on the subject - “DIY Light Bar - 40 x XM-L2 on copper.” (Also note Bigtoy302’s post #56 in that thread)