These are attached to any regulator you get, or should be. I don't think you need one.

Even that POS regulator you listed has this part. I use a POS regulator for propane, and have the fancy ones for my other gasses.

In theory, POS regulators will drop flow for no reason as you run them, but if you are running by feel, and if you are not running all day long, this does not seem to be a problem.

Propane will rot your hoses and other non-popane fittings. The guy I got my stuff from told me they would "only" last 5 years. If you don't use the system for long periods, you might want to flush the propane hose.