I'm currently commuting by bike and wanted to put a pair of permanent fenders to prepare for the coming winter weather. I ride a Jamis Allegro A2 with a rear luggage rack. I have a photo below of what the rear setup looks like stock and also a few pictures of what my bike looks like. If you zoom in you can see the front does come with an eyelet for a fender. The rear does not. I found an attachment by Portland design works you can put on the axel on on Amazon. However, I'm not sure they will give me the correct clearance. The fenders I'd like are Planet Bikes Cascadia bike fenders - 700c x 35mm. What should I do to get a sturdy mounted set of permanent fenders on my bike? Will I have issues getting it to fit with my luggage rack?
Use rack mounting eyelet (with longer bolt if required). This is usually considered acceptable but not always ideal.
Stabilise rear mudguard to rack instead of using mudguard stays
Use P-Clamps (often found in automotive applications) correct diameter for frame's seatstays to provide an eyelet to bolt the mudguard stays on to. Mikalor ones are a good example.
Use Paul H's method. Unfortunately this information is classified.