You will strain your entire drivetrain more with taller tires every time you take off from a stop. Running a taller tire effectively raises your final drive ratio, to where you're close to a 3.42 gear anyways. The engine will take more abuse from this than sustaining a few hundred more rpm's down the highway.
If you only change the rear tires for shorter height, you could be in trouble if you need 4wd, because you have different drive ratios front to back. Not good.
I have a half ton 4x4 suburban with a warmed up 350. I run 34" tires and 4.56 gears. This big beast of a SOB finally has some low end grunt with this combination. The truck gets moving sooo much easier than it did with 3.73's. The engine is much happier now. I drove this truck loaded with people and luggage from louisiana to NY all the way through the Appalachian mountains a couple months ago. Safe to say the minimum highway rpms were 2500, and at times sustained 2800+ for good distances. The engine is fine. Your imaginary not to exceed rpm limit is too low. Heck, the engine probably doesn't make peak torque until you're over 2500 anyways.
I say leave it be. Yes, you'll consume more fuel, but wouldn't that be the case with a 6.0 or a bigblock anyways? Look at it like this...how many tanks of fuel for towing in 3rd at 2500+ rpm's does a pair of gear swaps at $1800+ buy you? Or transmission rebuild by towing in OD?