Led bar design Electrical Engineer needed

Hello  I am looking to design a 5 channels led Bar, 120cm long, 4 cm wide and max 5/6 cm high. The 5 led channels need to be on the same PCB led module bar. I need the channels to be dimmable independently.
The lamp should have some degree of water resistance.  I need the system to have a main power supply, which then supplies 5 small drivers placed within the led bar, and not occupying lighting surface (therefore must be placed hidden in the bar).  The 5 channel dimmer should be outside the bat and close to the main power supply.
Both manual dimming or remote dimming work for me. It's important that the system achieves an efficiency of at least 94% (that is from the plug to the led only 6% can get dissipated as heat). It's also important the the cabling is neat, therefore single cable from the bar to the power supply.
The system bar should be made in aluminium and have only passive following, therefore both and drivers and the led chips must be cooled passively. Each bar is about 50W using Samsung and Osram most efficient led chips.  I will need a design for the led bar (heatsink), a design for the pcb of both the driver and led.
(The driver cannot occupy lighting surface, that is 120cm bar must be 120cm of emitting led chips). Specification for each component.  Please do NOT apply if you don't have experience with led bar development.
I will provide more details in pm.