Not a bad idea!

I added a few washers and sail with the rudder tight but not tied off.

This way if I scrape the bottom the rudder just kicks up. the downside is that I would have to mannually put it back down.

If you are reguarly in shallow waters like myself I feel that the friction fit is good enough.

An additional thought is that bungiees overtime will weaken and need replacment. I might grab an old bungiee and test it out though!