I’m a 12 too. I’ve had overshoes so you can get them (though I’d never use overshoes offroad). I’m not sure why you think sealskinz aren’t an option either.
My solution is size 48 defrosters with sealskinz. Works very well in the cold in the winter and some of spring.
But given you’re asking about all year round shoes, have a look at the N (for Nordic apparently) models from Shimano. My XC50N shoes are water proof (I’ve stood in a stream with them and stayed dry) but I’ve also used them in 35degree heat and I didn’t notice them being hot. Obviously water will come in over the tops but if you wear sealskinz with them, they could be a winter option.