Roof top spots advice please

Yes, I've searched. My issue isn't from battery to switch fuse relay etc but wiring the spots together. Individual power each to a junction box or chain them together? What's best? I have 4 x 50w led type with a custom made 40 amp 4 spot loom rated to take 4x55w lamps.

If the loom is made for 4 x 55w conventional bulbs it should cope with 4 x 50w LED units. Current draw should be around 5amps each, allowing for losses. If 40amp cable is used you should be able to daisy chain the units together. The joints at each unit should be really well made, especially at the closest unit to the fuse/relay/switch, as this will be carrying the full load.

If you have had a loom made go with that.