Use an integer field through the layer. NULL is understood as a FALSE unity 1 is TRUE.
1. Crossbase. At any time you can move from SQLite to MySQL and MySQL to PostgreSQL and Oracle, as well as exotic, and even a nosql database. Everything that supports the layer. If does not support — just write a new driver for the layer.
2. Not noticeable any significant changes in productivity and resources. Honestly, not much!
3. Convenient to use, convenient for programming, it is very convenient for standardization.
4. At any time you can extend the number of States of the entity. Pro stock there are 4 billion options...