Day 2... Wake up somewhere in CO and fish...
Day 3.... Wake up somewhere in CO and fish more...
Rocky Mountain National Park might be worth a look. If streams are blown out by run-off, you could hit the Big Thompson tailwater coming out right there at Estes Park. I did something similar last year. Miles of public access along the highway.
Day 4.... Drive to StL(stop and fish on the way while heading through KS/MO)
Kansas is my home state. And, no, it is not boring. Beautiful! You likely won't be wading in Kansas, though. Think reservoir tailwaters for warmwater species or fishing from shore.
By the way, I'd suggest taking U.S. 36 in the Northwest part of the state to see the Arikaree breaks, then swing down to I-70. Cedar Bluff reservoir, Glen Elder/Waconda lake, and Norton reservoir come to mind out west for fishing. (I've not fished them, and I'm not sure about water levels; drought affects those lakes.) Further east, Milford reservoir, Perry Reservoir, Clinton reservoir, Tuttle Creek, and Hillsdale are good and are reasonably close to I-70.
If it were me, I'd aim for Manhattan/Ft. Riley. Milford reservoir is regarded as Kansas' best but it may be low. Tuttle Creek Reservoir is also there. Try the Rocky Ford Fishing Area just below it on the outskirts of Manhattan, especially if they are releasing water. It's pretty, some of it looked wadeable during normal release, and has a historical coolness about it. (Indians and pioneers used it as a river crossing, and there are remnants of an old hydroelectric dam). Signs explain the history. Be sure to have shad patterns for Milford and Tuttle/Rocky Ford.
Pottawatomie state fishing lakes #1 and #2 are in that area, too, and there is the Kansas River which might get you into white bass and certainly rough fish. A little further south is Council Grove Reservoir and city lake and the scenery on the way to them is beautiful (you will like the Flint Hills in the Manhattan area).
You can investigate all of these lakes on the KDWP website as well as Rocky Ford.
Trout--the only place worth a look would be Kanopolis reservoir. It has a seep stream that they have been trying to make a year long fishery. Information is available on youtube and on the Flatland Flyfishers website out of Wichita.
Missouri: Truman tailwater and Lake of the Ozarks/Bagnell dam tailwater. These are warmwater fisheries and outstanding.
For trout, try the Meramec river at St. James. It's probably the most accessible from I-70 (You'll find it SE of Jeffferson city). There's a trout park there (some dislike the parks, but the river below it is more traditional trout water.) Google Missouri trout hunter for an outstanding website and Msissouri's conservation department can explain things.