I've ridden in the desert area you would cross, but I've only done it in late fall or winter. For me, riding it in August would be pure misery. Temps would almost always be over 100 deg. F. during the day. And if you're unlucky, you might flirt with 110 to 115 deg. F. Not fun and actually pretty dangerous. Once you've toasted across the deserts, you'll get all the fun of high humidity in the South to put icing on the cake.
To succeed on such a ride, you'd need a very high tolerance for suffering and pack ungodly amounts of water. I'd consider light covering over legs and the whole of the upper body to minimize UV exposure. Have some cash for motels/hotels/hostels to have a chance to recover with some AC. The most "comfortable" way to ride would be moteling most nights, of course.
The ride is, of course, possible, but why do you want to do that route at that time of year? Pure challenge and bragging rights? You could do a modified Northern Tier with about the same mileage. You'd still do plenty of sweating, but I suspect you'd have a more enjoyable time of it. Why not start in Alaska and ride south to the USA? Or some sort of loop tour in Western Canada? Jeez, lots of choices that would be soooo nice.
My 2 cents.
Have a great tour whatever you choose!