The term “nonconventional home” refers to homes that are used on a transient basis such as a motor home and boat. The interest, if otherwise qualifying for the home acquisition mortgage interest, is deductible on Schedule A. However, for AMT purposes the following applies:

Post-2017 - The acquisition debt interest related to a non-convention home is not deductible, but the Form 6251 doesn’t have a dedicated line for making a mortgage interest adjustment. Instead, it is combined with other seldom encountered adjustments on line 3 of the 6251.