I towed my 2013 mini and, if yours is like mine, it does not have a locking steering wheel. You do not need the round fob in the ignition to flat tow, but if you leave it in, the mileage will accumulate on the odometer. Without the fob, no mileage.
No need to disconnect the battery. In fact, you may need it if you have certain types of braking systems.
A supplementary braking system is recommended. If you get one that is powered by the mini battery, you will need to have a live power port, most likely the cigarette lighter. If that needs the fob to be hot, then that changes the equation. In such cases, a charge line from the coach to the tow car is recommended.
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.