I cook a lot of oysters on my barbecue, as the oyster beds are about a mile away, and I buy em in 25lb sacks. Heat and salt water together rust out barbecue parts really fast. So over the years my barbecue has become the Bionic Barbecue- or maybe the 6 Million Dollar Barbecue. this one is gas, so first I had to replace the burners with stainless burners. Then I replaced the lava rock tray, which was 16ga mild steel, with 14ga stainless, and a rock tray of stainless expanded metal. For the grill, I did exactly what you are talking about- 3/8" round stainless, on 3/4" centers. At this point, it is about 4 years old, and there is no rust or damage to the stainless. I fire it up hot for
10 minutes or so, then brush it off with a stainless steel wire brush before I put food on it. The 3/8" round bars are somewhat blackened, but they work just fine. Ended up making a second barbey for big parties, charcoal fired, just for oysters. It is made from 1/8" stainless plate, with another 3/8" round grill on top. With both of em running we can cook about 40 oysters at a time. Of course, the stainless works just fine for any other meat, fowl, or fish as well.