Bob,
Kent is the expert on the Flint but I have grew up near that river as well. The Upper Flint (upstream of Big Lazar WMA) is extemely susceptible to runoff. The slightest summer t-storm will muddy the river for days. With that said….the window to fish clear water is minimized.
As a general rule, the river fishes best in the heat of summer. I used to fish the river in a canoe….and now a Gheenoe. I would think a kayak would be excellent to traverse from shoal to shoal….then get out and wet wade. There is a nice mix of slow water and shoals.
I can’t speak to the lower Flint.
As Kent mentioned….Springtime around here is reserved for strippers 🙂 hybrids and white bass…….and the skipjack.