amishsixstringer, if you are really worried about the other 3 speakers just sort of "flopping around", go ahead and short each one. That's right, include in your switch that ability to disconnect from the amplifier while shorting the speakers together. By doing that, you will increase the rigidity of the cones. Sort of like putting an electromagnetic break on them and so, it will certainly change the resonance of the box and make the other speakers more like a piece of wood rather than a piece of moving cardboard.
Push in. Push out. Bush in. Bush out. Toke in. Toke out.
Ms. Remy Ann David