...I don't know if I would use stainless for anything requiring strength or safety such as frame members, it really isn't all that strong.
I know I wouldn't. Where you need fasteners to really do their job, like drivetrain, suspension, and frame stuff I always use normal stuff that was/is designed to do the job.
Although...I know you can get stainless good enough, but not many of us would have the money to pay for it. I worked at a shipyard and one of my jobs was helping assemble torpedo tubes, everything was rust/corrosion resistant including all the fasteners, and most of them were very high quality as you would expect... None of them were what you find at the hardware store.
As mentioned earlier
always use never seeze / anti seize of some sort on stainless fasteners to help prevent galling.
One thing most people don't understand is stainless steel is "stain LESS steel" not "stain
free steel"
Grigg