In four Caminos, I prefer to wear zip-off nylon hiking trousers, and to allow them to get, wet, muddy, whatever... They dry in about 30-minutes while walking.
If muddy, you can zip the bottoms off, wash and wring them out. They dry very fast, and can even be reattached when wet, allowing them to air dry while worn.
I have seen many folks with dedicated rain trousers. To me, they look like snow pants you wear when skiing., and are IMHO overkill. However, if you are so sweet as to be made of sugar, and you will melt if you get wet, then this solution could be for you...
My view is that bringing or wearing anything that does not have multiple uses is wasted weight and space, for you to have to carry every day. But, I respect their opinions.
I also considered and used gaiters on my first Camino. They lasted about a week, until I discovered the handy wash and wear capabilities of my nylon hiking pants. The gaiters went into a donation box shortly thereafter. It was simply too much effort for a small return, and on an item with a single use.
So now, I wear a poncho, and let the lower legs just get on with it.
I hope this helps.