People who have never had an engine failure usually never plan for one, and you read in the newspapers they were killed by a "freak" event/breakage/failure that had never happened before; if we are talking about home builts, a lot of things can fail, so just for interest, if we decided the glide area between Georgetown in the south and Leongatha in the north (for the exercise we'll forget about the nearest landable surfaces and we pick the midway point where we stop doing a 180 turn to bo back and start opting to land straight ahead), in your aircraft what altitude would you need to be flying?
The next question would be what would be the expected cloud ceiling for the flight.
I don't know how many people know the glideslope for the aircrtaft they are flying but I'd huess less than 100%.
The reason for the recommended routes are that for most flights based on the weather forecast you will be able to plop on to solid ground from a relatively low altitude if an emergency occurs.
Not illegal
Not it's not; we left the era where an authority would "outlaw" something and people would claim millions for their lost parent because the rules missed a minor point.
Today you have the duty of care for the safety of anyone you carry or hit etc. so you decided, and history tells us that if you don't want to lose the farm, you better be relying on a legally sustantive point.
Not recommended
This allows authorities to point out the danger, and since you have the Duty of Care you need to find something to ptotect yourself. Industry Safety Standards are a good place to start looking, and following Industry recommendations is a very good idea.
Not uncommon
One of the most common Bass Strait crossers was an overnight freight Bristol Freighter. One night the engine failed and the pilot went down, never to be found.
So sure people have made multiple crossings, one guy has even paddled a surfboard across, but again, you are the one that owes a duty of care; it's your pocket.