Thank youIt IS a rust problem, yes. And one that I know all too well in Southern New England. I get double the salt because I live on an island. But even with rust, the flex should last at least a couple years. Only lasting a year, it typically means rust PLUS excessive movement. You can't use a straight pipe because it NEEDS to flex. Otherwise, you transfer all engine movement directly into the rest of the exhaust. I wouldn't think you could do anything to prevent rust, because of the high temps. One of the big issues with the flex pipe fixes is that they cut out the flex part and weld in a new section. Often, the weld starts rusting almost immediately and then quickly eats into the collar near the top of the woven part, which produces a hole.
Coming at this another way, if you replace the whole pipe section with a Toyota-branded factory original section (P/N:174100A390; $426.45 USD) from the front manifold to the center section, you'll probably get 7 years out of it. If you use an "aluminized steel" (electro-coated with a barely rust-resistant coating) aftermarket exhaust section, you'll probably get 4-5 years out of it. If you clamp in a new stainless section, my guess is that a hole will form just ahead or just behind the clamp section. A stainless exhaust (as I mentioned above) is cheap and easy, if you still have intact flanges in front and behind the flex pipe section. You'll need 3 sets of new hardware and a couple exhaust gaskets. After that, it should last for at least 5 years, unless the actual source of your premature failure IS a broken/worn engine mount or a generally rough-running engine which vibrates more than it should.