The negative lead of a non-connected truck battery with dielectric discharging liquid inside with one of the caps taken off? Maybe even add a connection from the positive post to a chassis ground with a 1A inline fuse?
Try these ones:
https://www.crutchfield.com/g_510/Subwoofer-Boxes.html?tp=112#&nvpair=YCEnclosure_Type|Ported&nvpair=YCEnclosure_Type|Sealed&nvpair=YCWoofer_Size__@inches@_|12&nvpair=YCSpeakers_Per_Box|2...
Soft diaphragm tweeter, hard diaphragm mids and thick diaphragm subwoofer(s). I'd say high Qes and high Qms. Maybe you're looking for a Denon HU or Eclipse HU if you don't mind old/used equipment. Alpine CDE-175BT should do something.
You can try. Touch both wires together before connecting them to the speakers. If the HU didn't go on protection mode or burn a fuse, you should be good. (Leave it connected for 5-10 mins to see if it'll burn the fuse.)