Since there is no looking back now, there is only moving forward, MCPCB seems like the only logical choice. Will try to find a way to design the files in Kicad. 

From what i gather here and there, no vias (or very few) is allowed. 

It´s possible to make it with 2 copper layers. Either with aluminium sandwiched in the middle or as a backing plate. 

Im thinking to maintain the fan´s.

Now, having come to the conclusion, that the heat-dispersion (cooling) and thereby the mechanical buildup of the finished design, is fundamentally important for a good and lasting design, the inevitable question arises. There are techniques of which the pcb maker connects the aluminium or copper layer of the metal-core pcb directly to the heat-pad of the high-power LED. This technology has different brand names and probably different ways of achieving the same goal. Now back  to the question. There is no question about the advantages of such a direct path for heat to flow. The question is how and how much. If a special tool for the process is needed, cost goes up. Especially for prototypes. 

So what´s the plan?

My plan is to do prototypes the regular way of doing Metal-core pcb with a layer between the copper and aluminium. The copper thickness will still be 105µm. This way I will validate the design and at the same time learn from the manufactures doing direct heat-transfer MCPCB pads.