I know you said you have limited access to pulldowns but....I love this exercise....
"Long-pull triceps extension also hits the long head of the triceps. It's a favorite exercise of Larry Scott and if there ever was a secret exercise for triceps, this is it. When done right, it seems to pump the triceps to double their size. You'll have to improvise a little when doing this exercise. See the picture for exercise description. The pulley shouldn't be to high, about 6 feet, and instead of the twin pedestal bench, you can use two benches facing each other. "