Tectro makes a version of the streight pull/long arm for BMX with somewhat shorter arms that work ok with slr brake levers, good stopping power but prolly not enough clearence for fenders.
Try regular long arms with a travel agent, Sheldon Brown has an article bout this stuff. I have found long arm brakes work ok with old non-areo brake levers too, thats how I got those brakes on my gravel road bike and still use a drop bar.
kev