NM to MD in August: I-40 vs. I-70 (best, trip, summer)

[okgo]

So in the middle of August we're stuffing two cats, a pair of temperature-sensitive salamanders and a bunch of vinyl records into a Corolla and driving them from Santa Fe all the way to the east coast. We want to avoid blistering heat and thunderstorms, if possible. I-40 is more direct, and what we took last time we did this (minus the cats and salamanders). I-70 adds about 3 hours to the trip (jumping up to Colorado on I-25 and catching it there) but means we avoid the blast furnace that is TX and OK in summertime, plus last time we got caught in some crazy storms around there and the cats will be under enough stress. Finding a convenient stopping point seems harder, though; I don't know if the cats can deal with more than 10 hours at a stretch and getting to 70 makes the first leg of the trip longer. Thoughts?

[arrgy]

I drove with 2 cats from Phoenix to Philly. Went across I-40, had no problems with them at all. It may sound crazy, but I suggest leaving at night. The most dangerous part of the trip is through OK. And your best bet is to do that early in the morning, you don't want to be in that area of the country in the afternoon. Its about 10 hours from OK city to Santa Fe. So you could even stop in OK city if needed. I wouldnt go I-70, that extra 3 hours isn't worth it.
The only other option is 54 through Kansas to I-35 to I-70. But what's really the point?

[okgo]

Leaving at night sounds like a great idea, actually. If things go awry (they usually do), is driving through Kansas in the afternoon any better than OK?

[arrgy]

No, its the same terrain and geography.