Hi Chris,
Don't you have a hole for a thermistor in the centre of your heatbed ?
So you'll be able to fix the thermistor from behind. It will be pretty the same.
Don't worry to get the perfect temperature measurement, aluminium catches and diffuse temperature pretty well.
Maybe it's more interesting to print on the aluminium plate on tape or something ?
For the wires, Serge used to fix the ramps inside of the box on the left pannel.
I would keeps the wires away from the Z axis mecanics and turn the connections of the bed from the back to a side.
++JM