I took some friends’ advice and added a little Swiss cheese to my engine mounts. It was a heck of a lot of work to save less than half a pound. Beyond about a 1/4″ deep, hole saws can’t clear the swarf very well and get rather fussy. My nifty aluminum-cutting router bit made quick work of beveling the edges, though. I still might add some holes down the center of the base plate. It’s not quite as thick, and a couple of holes might help keep crud from nesting in the channel under the engine.
I’m still undecided about a finish. I don’t really want to spend the time to polish the surfaces. I could just give it a brushed finish, but paint might look better, longer. I’ve thought about either gloss black, satin black, but I have some leftover Gentry Gray wheel paint; painting it to match the wheels might look really good.