My father in-law has not been living in his house (primary residence) for nearly a year.

Understanding Michigan property tax laws may explain what you are seeing.In Michigan, property taxes reset upon sale and then are capped at CPI.  

Just lean heavily on educating yourself on the laws, notices, etc. early on.

If either argues about the approach you can simply fall back on the 'law'.

We hired a law firm to take them on.I have heard from many people that the reviews of people stating that they good experiences are them and 100% fake. 

In Florida, land trusts offer some unique benefits similar to an LLC, such as asset protection and anonymity, which makes them especially appealing in creative real estate deals.While LLCs are often more widely used because they’re familiar to investors and offer clear liability protection across multiple states, land trusts can be highly advantageous in Florida due to the specific protections our state law provides.

Additionally, the landlord laws here are more investor-friendly.

Check your state's laws about tenant possessions.

We have a pretty rural place and Idaho has some of the most strict laws around marijuana use so that hasn't been an issue for us.Smoking in general has been a problem a couple of times.

Sure- Idaho has state laws outlawing rent controls.