Hook up of new blue flame vent free heater

[sdroots]

We have a 10,000 BTU/hr blue flame heater on order. We intend to mount it permanently on end of penninsula of our '07 3000RK. We hope to tap into the 3/8 OD copper tubing that feeds the range. It's about 6 ft away and a pretty easy run. We understand that the heater has a 3/8 female pipe thread on bottom. Can anyone explain how we should plumb it up? Ideally, we would have a shutoff valve. Our concept is to special order the hose, buy the necessary fittings, and install ourselves. We've made a few stops at hardware and propane stores. They seem to think we'll need to tap in with a 3/8 male flare Tee. This would require flaring the ends of existing copper tubing. We're favoring rubber hose rather than copper tubing to gain flexibility. Any hints would be appreciated.