Logical - you ask me about logical? :?
My "normal" trip out West usually has me putting in an 1100 mile Day 1, usually getting to Western IA before I stop. Then an "easy" 10 hour run to Denver! (Lately I've been running I80. I70 is OK, but, for some reason, I hate using it. More big cities to negotiate, with associated traffic/construction issues).
This September, CHW and I are going to try to get to Grand Junction by the end of day 2. And then take a leisurely drive the next morning to set up camp in Moab.
On paper, your itinerary seems OK, but I think you could easily get past Indy on Day 1. Go as far as you can - that first day is when you're in the best shape. Set yourself up for easier day 2 and 3. The key is to start very early on day 1. (4/5AM?) That way it'll seem "natural" to run to about dinner time (or later) and you'll be a lot further West than Indy. Besides, on your original schedule, you'll be crossing western CO with the sun in your face, it'll be a more enjoyable drive (and picturesque) if you're doing that earlier in the day.
Of course, I'm not towing anything either, so I'm not sure if you can maintain my insane pace anyway.
Hey - why not try this on your trip to St. Louis coming up - see if you could do this in one day. On paper, you should have no problem- staying awake though is another issue!
Anyway, glad to hear that you guys are planning to head to Moab in Oct - it's going to be a bigger bash than ever!!! You'll have a great time.
Mike in NJ