On my old touring bike I used SKS full fenders with a mud flap, they worked good except they constantly needed to be adjusted, which was difficult to do. So, when I got my new touring bike, I decided to try something not so full and went with Topeak Defender IGlow (not sure what the IGlow means since nothing glows on it), they keep just as much water off as the full fenders did. I did cut a piece of black Gorilla tape about 6 inches long, I then put about an inch of it on the back top side of the rear fender, folded it so there was about an inch on the underside of the back of the rear fender, then pressed the tape together so they stuck together...that was my mud flap, and it's lasted for 3 years so far with no signs that it needs to be replaced. That tape only added about 2 inches to the rear of the back fender, not sure if it's doing much though, maybe? Someone could make that tape mud flap longer, but I wanted it a bit stiff, I had I gone with a 12 inch piece instead it may have flapped around? Anyway, with a lesser length fender I get just as good coverage as I did with the full-length fender, nothing gets wet from road spray, not even the pannier bags. While the fenders still go out of adjustment after miles of banging down rough roads, it's a lot easier to readjust the fenders since Topeak uses a quick open lever that allows the plastic rods to move, then lock the levers down once you're done, and I'm only dealing with one set of rods instead of two like the SKS, and the SKS required tools to adjust the rods I don't need tools with the Topeaks.
For that reason that I discovered that I don't believe full coverage fenders are necessary, at least in my experience.
One of things on my new touring bike is that the bike came with 45mm tires, the Topeak fenders barely cleared the tires by about 24th of an inch on the sides and about 1/8th of an inch on the top of the tread of the tire, so if the fenders went out of adjustment just a tiny bit, either by road vibration of something being picked up by the tires, I had to correct the alignment; now that I have gone to 38mm tires I doubt I will have to adjust the fenders nearly as much if ever unless something gets picked up by a tire and hits the fender knocking it out of adjustment, I haven't used the bike since I got the tires this year to know for sure but just by looking at it I have about 1/4 inch clearance now on the side and about 1/2 of an inch between the fender and the tread.
The Topeaks also don't make nearly as much noise if any vs the SKS fenders, those SKS fenders were noisy. And since the Topeaks are not full size, do not use steel bracing, they're lighter in weight.