Salsa Marrakesh takes up to 700x40 tires with fenders. Rule-of-thumb for fender sizing is tire size plus 10mm, so to fit maximum size tire you'd need 50mm fenders. I have Velo Orange Zeppelin fenders (52mm) on my Surly Disc Trucker (maximum tire size 42mm with fender) with no issues.

It is possible to make tire-to-fender gap less than 10mm, though not by much. Also, aluminum fenders can be bent slightly to be a bit wider or narrower, the trick being to deform equally along length so they don't look bent.

Of course you can use smaller tires than 40mm and smaller fenders than 50mm, but if you do it prevents you from using larger tires without removing the fenders. For example, 700x35 tires with 45mm fenders means 40mm tires would likely not fit without interference with fender. Appearance-wise the bike looks best when the fenders closely match the tires, so that there is little gap between them. Water is less likely to splatter outside fender when the gap is narrow.

Velo Orange offers several fenders that will work for your application, depending on tire size you intend to normally run on bike.