Hi there I was able to finish this with three stars in plenty of time using this strategy:
Clear wood and stone build all buildings immediately and upgrade sawmill as you clear down to the first cableway and build.
Once you have enough material build second cableway that leads to the merrymaker hut and build it.
Send the first merrymaker to the sawmill and keep him there producing wood.
Once you have enough materials upgrade first mill to level three.
Upgrade merrymaker hut to level two and send second merrymaker to the mill and keep him there.
Build cableway to the sorcerers and fireman and build both.
Clear the obstacles near the other two mills and build them.
Once you reach 50 food upgrade the merrymaker hut to level three.
Thank you that worked great! I had to NOT upgrade the second and third mills and just leave them at level 1. Frankly, I'm not sure I even needed them. I got the first mill upgraded asap and then the second merrymaker as you suggested - so had one in the wood shed and one in the mill working their butts off. Worked great!!