Hi Ale,
I have taken a look at your google solution and think that if a smooth faced filter housing were used it would be much less easy to catch on an obstruction. It does seem that it is the moulded nut on the bottom which makes the housing so vulnerable. If this catches on an obstruction it gives purchase to it and so levers it off. Fitting a smooth faced housing may well encourage the obstruction to slide over it instead.
Of course, it all depends on what kind of obstruction that you ground the car on, wether it is smooth like a traffic calming measure or solid steel upright like a gate keeper. I like the thought of solving the problem without having to resort to a sump guard but have the feeling that having a plate running under the engine will encourage the car to slide over the obstruction or give loud warning not to proceed.
