The quick connect fitting and a regular air hose fitting are not interchangeable. The quick connect fitting is made of brass and has much tighter tolerances than a plated steel air hose fitting; in an air hose, a small leak around a fitting is no big deal. With a propane hose, it could be fatal. Plus, there is zero chance of the brass fittings sparking if they hit each other. FWIW, I looked into this very thing when I was modding our Weber to use the trailer's propane system.
Here is the proper quick connect fitting for a propane hose:
Camco 59903 Propane Quick-Connect Fitting
As for the hose, I priced out having a custom hose made from a local propane dealer, and the price was such that it was actually cheaper to buy a pre-made hose in the length I wanted.