Since you're coming from relatively low land country, my guess is that you have little experience with high density altitudes. Around here in August, the DA can be over 8000' off of a 5000' MSL airstrip. What that does to your airplane's performance can be shocking, if you've never experienced it before. Here's an example:

Hard to believe, but both guys walked away from this. They'd tried to take off from old Downtown Fort Collins Airpark, which was 5300' long x 44' wide at just under 5000' MSL, in a newly purchased 150hp Citabria, which they'd bought in Oregon, if my memory is correct. My recollection is that they were not overloaded, but close to gross, failed to lean, and tried to pull it off too soon and too steeply.
So there are a couple of things you must do at high density altitudes.
You must, absolutely must, lean for best power. The way I do it is as a part of normal run-up, lean until the rpm just starts to go down, then enrich about half an inch with the mixture control. That has worked for every airplane I've ever flown (other than turbo'd airplanes, which are a different breed of cat). That includes Cessnas, Pipers, Beeches, Citabrias (both straight Citabrias and Decathlons). With or without an engine monitor, that seems to work as well as any other way you might have heard about.
You must pitch up much less aggressively than you're accustomed to. Think Vy, not Vx, and realize that your climb rate will be much less than you're accustomed to.
Also, don't judge your landing speed or take off speed by how it "seems", because at high density altitudes, the true airspeed and consequently the ground speed will be much increased. Rely on your airspeed indicator, because you'll use the same indicated airspeeds that you normally use--they'll just "feel" faster, because you'll be traveling over the ground faster.
There's lots to see across Middle America. It can be a really fun excursion. Just take it easy, and like has been said, weather will be the biggest issue, as it is with any cross country trip. Have fun!
Cary