No, not at all! Brass is a "soft metal", if you're concerned about stress stainless would be a much better choice IMHO. Keep in mind I'm not familiar with the hardware you're talking about, just speaking in general terms. (Photobucket isn't working on this computer for some reason!)
I have to say.. I am in the building industry & what I understand is stainless steal is not the same as it used to be. Depending on were it is made. We have to be careful that we are using stainless with the right amount of Chromium over 10.5%. Just because it says 316 stainless.. is it?
Just wondering if you ever found a source for these? I am replacing the deck, spray rails, and "outer transom" on my '59 Erie. I am not missing any of those nuts, but did make a small attempt to find replacements "just in case", but could not find any. Needless to say I've been VERY careful not to lose any.