If the tank outlet valve and regulator are where you can get at 'em the Extend-a-stay type adapter is your #1 choice
The link shows the actual adapter. The full kit Comes with both a 10' Tank to grill hose (The Grill end has the same fitting as the top of a "Throw-away" bottle as does the OUT port on the "X" fitting)
And a 5' "Tank to RV" hose that fits the inlet port on the "X" adapter.
The inlet has a small (about a quarter inch) brass threaded hole.
One of the first "modifications" I made to my RV 15 years ago and used both of the extra fittings (Grill side and external tank side)
Check valves protect you from many "Oh ****!"s that can happen.
Flame King adapter only
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times