Hi, as you say you are restricted by the moulds you have. In an ideal world you should aim for the resin to travel the shortest distance, so as you say front to back is the way forward.I would (if the mould allowed) have the spiral the full length of the front edge with the resin feed in the middle and the vac in the middle of the back edge (where the up-turn is). You could stop the mesh just short of the up-turn, so a nice simple rectangle of mesh. If you put a 50mm square of mesh and breather cloth under the vac outlet this will choke down the resin feed once in reaches the vac outlet allowing the upturn to saturate without the need for mesh. You can also leave the resin feed clamp open for a good 30-60 seconds (depending on the size of the part) after the vac is clamped off giving you a resin rich part. Because of the moulds you have you can only have a small feed spiral and the resin has a long way to travel. Even with mesh I would think it was a pretty slow infusion.
Regards Warren