If you want two chains for the looks, it’d be fairly simple to set up a double-sided fixie. Install fixed sprocket on the left side, using plenty of torque and red loctite. Install freewheel on the right.
Another, messier option is to deliberately cross-thread a LHD f/w ono the fixed sprocket side of an aluminium flip-flop hub.
F/h is hardened, aluminium is soft. Run a file around the threads a couple of times to take the diameter down a little first.