i have an 8hp Tohatsu/Nissan on my 12' jon boat that hasn't been taken off in at least a decade. And I've pulled it hundreds of miles. To keep it from bouncing I just put it in reverse and that engages the lock so that it doesn't lift up.
"Life is a matter of luck and the odds of success are in no way enhanced by extreme caution." - Erich Topp, German U-boat Commander, 1943.
When in doubt, set the hook.