How can we add an Accessory Dwelling Unit to our property?

We need to add a mother in law suite to our property, not in the home. We have a new pole barn-workshop that could be added onto or we could buy a tiny home (amish shed). We need help finding the right balance between physical cost of the structure, physical cost of connection to utilities and location. The Barn maybe the way to go because i can easily connect it to the septic by adding a toilet versus tiny home route but would like your opinion taking into consideration of Grattan Township's Regulatory Ordinances. I know Grand Rapids is ADU friendly and has created a path forward and will use this as ammo if a variance is required. If Grattan's ordinances don't favor ADU's, then i will need a cost to fight.