I switched out the Carf nuts for two pairs of Secraft wing bolts, and metric thread. With the original plastic nurl nut it was very hard to tighten, I too have large fingers and had great difficultly getting them snug .
If needed cut some 1/8 plywood and shim and hysol to the desired height or change servo arms as some arms are closer to the servo base and other are farther away giving better clearance. The servo screw I used had a 2.5 head hex and i used a small 1/4" racket from princesses Auto and 1/4 drive, sockets are from gear wrench that it all fits inside that tight space.
