I'm getting ready to put new molded hood insulation on my cowl hood. I was thinking of lightly "fogging" the underside of the insulation with some clear enamel in an effort to make it more water resistant, and hopefully last longer. Is this a good idea, or a bad one ? Thanks, Ron.

Bad idea, clear will not stick to hood ins. a spray type wax is a better choice, like the kind used for out board motors to keep the water off it will soke in and not flake off like a clear would. I did it to my hood ins, and it will with stand the heat as well as weather.

I'm not able to find this type of wax; would 3M scotchguard be something that could be used for sealing the insulation ? Thanks, Ron.

Yes you could use a scotch guard product, but heat might be an issue Same as if you used floor polish which I've seen done it looked good.