My high pressure BBQ adapter includes the external tank port. Plus I can connect to any BBQ that needs either high pressure or low pressure. Low pressure propane fittings are common on RVs and you may need to remove thte BBQ regulator as the use of 2 regulators may give inconsistent propane pressure.
This is my high pressure adapter with a El (for hose routing considerations) and a shutoff valve. The top external tank port is for additional external tank. The BBQ connector is the standard 1 lb 1" screw on propane bottle type.
Hoses with the standard 1” screw on adapters are available. And an adapter for the standard BBQ regulator fitting are available. Propane stores can also make custom length hoses however I use 1 or 2 12' hoses as needed.
Here are the parts that connect to any grill with a external tank connector.
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland
Bob