If your tripod head uses an attachment plate like Bogen, you could just drill thru the monorail and bolt the plate on with counter-sunk machine screws. Get some tubing that the screws fit thru, cut 2 stubs that just fit inside the monorail so you don't crush the rail when you tighten the screws. You can tape these to a long dowel to fit them in place. Do use 2 screws so it doesn't rotate in the field. Standard bolts will work also, they just don't look nice.
Just a thought.