The only problem is the slot only 5/32''wide for the rudder made from 1/8'' aluminum...

I also found this out with my skeg and started to use sticky tape over the slot for beach launching until I made a properly designed skeg with bosses around the pivot point. I had two times the width of slot compared to this so had room to accommodate ever increasing grades of grit,seashells etc.Now it's about less probability of jamming.A pull string is also a good idea if you have someone willing to get their arm wet.
cheers from Paul.