We have used a 5 HP Nissan since we bought the boat several years
ago. As long as you don't gun it in reverse you should not have a
problem. Ours does not have the terrible vibration you speak of.
There is some, though. The tape idea sound like it may be worth
trying. The weight of the 2 stroke is much nicer. I am not looking
forward to having to replace it with the 4 stroke.