I'd skip the stainless. The problem with stainless bolts is that in the presence of an electrolyte (such as salt water or even moist salty air) it rapidly accelerates galvanic corrosion of the surrounding materials. The bolt itself won't rust, for sure, but it will accelerate the rate of corrosion of everything around it.
In the presence of an electrolyte, stainless fasteners are mostly only appropriate for stainless materials. When used with steel or aluminum, the significantly different galvanic potential creates a galvanic cell. You can actually measure the difference with a voltmeter in some situations.
A better solution is to focus on fasteners with a high quality zinc plating or galvanization. Even when some of the underlying steel is exposed, the fastener does not rust in the presence of an electrolyte, because the zinc sacrificially corrodes, thereby protecting the bolt itself and even the surrounding metal. However, once the zinc runs out, regular corrosion will begin on both the fastner and the base metal.
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When coupled electrically, dissimilar metals create a galvanic cell, the intensity of which is driven by the difference in electopotential as shown in the above chart. More cathodic metals are protected by more anodic metals. The more anodic metals are eroded as a result.
This is the same reason boats have zinc blocks on the hull and your water heater has that one anode you have to replace every 5-10 years. It's a sacrificial anode designed to protect the surrounding metal. Zinc coated bolts have the same effect; though they aren't necessarily intended to protect a large amount of exposed metal around it. If you replaced those zinc items with stainless, sure they will last forever. But they will actually begin to accelerate corrosion of the metal around it.