There are two things that might help.. First, the regulator may need support (Assuming that is what is on the other end of that line)
but to replace it with a hose you need a propane professional. Not a "Pump jockey" refill technician but a real propane professional..
how to find one:
Google "propane" followed by your zip code. Like the Propane 12345
Now scan the responses and look for a company with DELIVERY TRUCKS in their logo.. Start calling them.. Odds are one of 'em will have what you need. Likely on a rack on or by the wall.
Option 2 if in Quartsite AX.. Pit Stop has 'em.