drive no faster than 80 if you don't want to worry about it. you're probably ok doing more than that, but if you really want to not worry, i'd stay below 80.
personally i've maintained a steady 95+ for huge stretches without issue. there were a couple times i was sure i was nabbed, but the cop always either exited without pulling me over or never left the shoulder. once i crested a hill at nearly 100 and there a cop 1/4 mile down the road sitting in the median, but he never pulled out, so who knows.
edit: i should add that i almost always use some fool in a cadillac or corvette as bait. i stick behind the fastest, flashiest car i can find and stay about a 1/2 mile back.