I've got a 1975 18' Mark Twain with an I/O. We use this boat for tubing, skiing, wakeboading... I was thinking of installing a swim platform on the back. Can anyone suggest a manufacturer or place to get one. I want something that will take the punishment of being used on a weekly basis. We are a big family (8 of us) so there is normally at least 5 people getting in and out of this boat.