Towing speed for small pop up ?

We usually cruise along at 70 mph, but there are times I've had to go faster than I should for brief moments due to someone trying to drag race me as I try to pass, then slows back down when I pull back in behind them......I'll deal with this a couple of times before I just go for it and do what it takes to complete the pass.....I won't post the speeds, don't need to get beat up here, but do return to my cruise speed after the pass and watch the person fade back.