I wouldn't use it for what your talking about. Hobie used to use one of their products between the metals and there were still issues with corrosion. Now there's stuff that pretty much stops it.

A rivet properly installed isn't going to leak. If you want to use it to dab the mandrel holes, fine.

Tefgel . Get it, use it. It comes in a small syringe with a brush. On smaller parts like pad eyes forget the tape and coat all the touching surfaces with it.