Yeah i WAS going to do it after seeing this one locally.
I had a bracket and everything, but after some research and deciding I would be fishing inshore/shallow water more than offshore so I thought better of it. Instead I went with a jack plate and that helped me gain a good bit of room in the rear so I'm happy. Unless you have a full transom 18 that had a sea drive I wouldn't do it. Even then if I did I would use the shortest, lightest bracket possible and no more than a V4. I plan on changing to V6 power (150 or 175) so a bracket is a no no for me. IMO the 18 is really a$$ heavy anyways. I have moved two of my three batteries to under the console to combat this and it has helped tremendously. The boat sits nice and level at rest now and planes out wonderfully. It also handles at speeds MUCH better as a result. I would also do this for sure on a bracketed 18.
I think its definitely possible if following these few parameters. if you do it keep us updated! id like to know how it goes!