Ok, so having to go back to filtering my own Propane prompted me to hook it all up and get a photo of it like I promised.
I invert the cylinder about every 2 hours.
When it's upright, all input valves are wide open. I throttle the output valve on the machine to get the head pressure about 100psi above the input pressure. This rapidly cools the tank as it uses the tank as an evaporator.
When I invert the cylinder, I open the output valve wide open and throttle the input valve on the machine. This makes sure the input line (with the big filter) has a solid liquid fill. It flashes to gas in the input valve block before being compressed, condensed and sent back as liquid. This slowly warms the tank.
I've got a spare fridge compressor here somewhere that I'm thinking about setting up for a long-term recirculating filter device. It depends on how effective I can be at regenerating the dessicant in the filter. I hold it under a high vacuum and hit it with the mapp torch to drive off the moisture trapped in the dessicant. Apparently it needs to get over about 450F to do it properly, but I'm not sure I'm that game!