You share the lease, you share his payment history, and you give a total of what is owed.

I estimate high of what the bill would be and put it on their lease, I have not had any issues this way and if the water bill goes up, I will increase on the next lease. 

Signs of this are poor lease quality, maybe M2M tenants, high expenses (unnecessary things like high trash bills, internet, cleaning, security).

I am considering getting into some commercial investments and think I want to go down the NNN route. Are there any books or resources you can recommend to get me started with the basics?

Hey @Devon Moore not sure where or why you'd lean towards a land lease unless that's standard for this developer.In my experience its difficult to capitalize deals with ground leases involved.  

I am not sure if you are in an area where keeping the heat off could be a lease violation or you have that term in your lease.

I have solid commercial leases, but I am interested in what landlords request of prospective commercial tenants to do the due diligence?

A local lawyer approved lease worked for the tenants I chose; I took in rents on Apartments.com.  

Are you allowed to lease the unit?

Someone with a voucher may still want to lease your unit even if the rates are above market because they are not paying.