MFR: Actually harvesters have quite much larger AoE, and will also stretch upwards - this to get all the branches of a tree. I'm using a 3x3 Sakura wood farm with an unupgraded harvester, and it picks down at least in a 7x7, and at least 10 blocks high.
SC: Yeah but the farm is inside my barn, which does not have sky access! Smart idea with the CC+Holding track though.
I'm currently testing out the straw golem + wood golem (teching was surprisingly fast) and they seem to work well though, for the small scale this is.
This is the mechanic of when it encounters wood blocks only, not other types of crops.
an unupgraded harvester will only look in a 3x3 area in front of it for anything harvestable, and when it comes across the logs. Then and Only then it actually harvests upwards and outwards.
if it encounters wheat, berry bushes, potatoes, anything like that, it doesn't search for the extra bit to harvest, it only harvests that block