I have edited a couple of harvesters with specific features that can help you harvest for longer periods without the need to empty the harvester every time, especially when working in large fields.
Modified Features:
The harvesters have increased capacity of up to 5 different choices including the default capacity (a multiple of 3)
The speed has also been increased for larger maps like Juotca 16X
I have also added a unique feature that allows you to choose the drop area width for the straw swath. This can help farmers with larger working widths that lead to a mountainous straw accumulation at the end of the field thereby preventing the harvester from turning when harvesting.
All these features are available when customizing the harvester during purchase.
Happy harvesting!

Credits:
Giants Software
Farm Adventurer
Original link (Modsfire)