Rake is just part of trail, which is a ground plane distance between the line thru the head tube angle
and the Plumb Line down from the axle ,,

one option in a fork is increase the distance Below the fork crown race to the fork blade tips
as you reduce the radius of the wheel By Opting for a smaller wheel whose smaller radius
will move the clearance to the Mudguard forward ..

Longer blades , or below the crown race the fork would have a thick tube down to shorter fork blades

so the relative distance from the top of the wheel to the fork crown is relatively the same ..

" suspension corrected forks" do this so the frame head tube angle does not steepen as it is dropped.
a frame builder could custom make such a fork , and also have the option to lower the C-of-G of the load in your Porteur rack.
another benefit of using a smaller front wheel ..
Georgina Terry use 24" front wheels in bikes with full size rear wheels 700c..

Though her frames, in their design, with shorter fork blades,
lowered the whole Crown lower Headset and used a Longer head tube and fork steerer
as the smaller wheel was being planned for..





./.