What are the gear ratios and tire sizes involved? Might be able to strike a compromise between running the higher rpm and trailing in 4-low.
And if you can run the 20 after all is said and done, the low is just a bit lower than the 205 anyway.
I used to run mine at 2700-3000 all day long down the freeways around the state with no ill effects. Except on MPG that is. But I used to get 15.5 at 55, so the 70's still had me in the 12-13 range with a manual trans, 32" tires and 4.11 gears.
Maybe you can still get where you want to be too, even if the auto will keep the freeway rpm up a couple of hundred, and use a bit more of the power to get it done.
But here again, gearing and tire size are a key component, no matter what.
Good luck.
Paul