One tank is fine for your 27. They last a long time for just cooking. The world does not end if you run out, but you can monitor the weight pretty well anyway and get refilled before you run out. There are small ones available too; depends on how much you use it. Need to be designed for horizontal or vertical.
__________________ "I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard