That element can be cleaned quite easily by soaking it in a mix of white vinegar & water (50/50) for a couple of hours. You should probably also flush out the residue in the bottom of the tank using one of these flushing wands before you use it again.
It's possible that the element has blown and ruptured, that would allow water in the tank to short the two exposed ends of the element and allow current to flow creating what is in effect an electrode boiler. The high resistance would limit the effect of the element, but as electricity takes the least path of resistance, would not necessarily cause a breaker to activate.
I have seen this happen in commercial and residential immersion heaters, and see no reason why it couldn't happen in an RV heater. If you have a multimeter, check the resistance of the element, it should be quite low. Also look for damage near the bend in the element.
Electic elements will crud up no matter what you do.
Now if you want a lot of hot water.. you can get a higher temp T-Stat.
That may help
else when you shower use (Atwood heaters) both electric AND gas)
I went "Slower" with my electric.. helps on 30 amp sites.