Murlin,
I think your're looking at two issues here. One is removing generated heat from the interior of the coil and the other is the possibility of circulating currents in the multiple strands.
To avoid dead air pockets within the coil, it would be best if you could use a single turn per layer. With 6 in-hand this could be reasonable. Avoiding winding crossovers is the point. Also, bonding the coil together with a heat-conducting agent will help. See:
http://www.fieldlines.com/story/2006/10/21/61110/798
I'm still not sure that circulating currents are a significant issue for strands of the same exact length. Certainly, Flux's suggestion of transposing coil interconnections should minimize the problem if it exists to a substantial degree. For further discussion on this see:
http://www.fieldlines.com/story/2006/12/15/16162/136
Another suggestion is that you avoid casting the stator in resin. Casting is a real mistake for higher power machines even though it's often done.