Solid state device for switching (muxing) a bipolar high current signal
I did something very similar (about 15 years ago) in order to signal over a 100 metre loop being used to inductively power multiple "stations". 

Using just on-off electronic switches did not provide the isolation I required. I added shorting "switches" at the output of the power switches to effectively form a very high ratio voltage divider. ie simplistically Vout ~= Vin (Ron/(Ron + Roff)). Where Ron is the on resistance of the shunt switch and Roff is the off impedance of the main power switch. (I say impedance for the latter as while the on switch resistance dominates, the off switch capacitive coupling become significant). 

For AC a normal MOSFET switch is not able to handle AC signals applied relative to the switch. This is because the body diode conducts when reverse polarity is applied even when the switch is off. The (or a) solution is to use two MOSFETs in series in opposing polarity. Source to source, gate to gate and the two Drains become the AC input terminals. For eg N-Channel MOSFETS driving the gate positive relative to the source turns both FETS on and connecting source and gate whether by a resistor or opto or whatever turns the MOSFETs off.  The g-g an s-s connection works because MOSFETs are two quadrant devices and when turned on a resistive polarity independent connection is provided from drain to source.

A challenge is to provide power supply to the gate drive which floats at about AC zero crossing level when the FETS are off and which depends on AC signal level when the MOSFETs are on. This can be done with an isolated power supply - a cheap enough solution nowadays, or some care with resistor and diode feeds from supply rails or for experimentation a local battery.