I'm in the same position as you. I have a pair of 26x1.35 Schwalbe Marathon Plus tires I use for commuting and touring. (I highly recommend them as I approach 4000 miles with ZERO flats). I just bought some P50 fenders and a pair of Innova 26x1.9 studded tires (the sidewall actually reads 26x1.75/1.9) for my new LHT. The snow tires are a bit narrower than the fenders and the LHT frame (54cm) allows plenty of gap between the fenders and the tires. I haven't ridden in the snow yet, but I'm hoping this combo will work ok. The fenders look great with my Marathon Pluses. I had wide mountain fenders on my old commuter (a hardtail mtn bike) and they were much wider than I ever needed, even for snow tires.

So, I say get the P50s. The silver ones look sharp with their stripes:
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