Since you stated you're going to change plans and NOT come to RMNP, I won't address RMNP and camping in this area.
I've made that drive from Colorado to Indiana many times, and you're going even further as far as mileage is concerned. It's a solid 1500-1700 miles, depending on where you are in Indiana as your starting point and using GTP as your destination. Our trips have been to the NE corner of Indiana, so we've used the I-80 route before. I can tell you it's a hard 2 day drive; heading back that way later this year, going to do it as a 3 day drive instead. You have 2 drivers, so it could be a moot point for you. Just sayin'. :)
Here's some information/suggestions to help you get there. If you're going to do it in 2 days, the halfway point could be in the Omaha/Lincoln NE area. There's some good places to use as your stopover park, just off I-80.
We've stopped at Pine Grove RV Park/CG in Greenwood, NE. It's about midway between Omaha and Lincoln and is a good choice for a stop, and is right off I-80, easy off/on. A bit of highway noise, but not unbearable.
There's also the Eugene T Mahoney State Park near Ashland, NE. Another good consideration and also convenient to I-80 for off/on.
If you decide to make a 2nd trip out to RMNP at a future date, hit me up and I'll give you the scoop on where to stay and when to reserve in the Estes Park area!
