Roadtrip thru ND/Yellowstone area, first time to the area, stupid newbie question.

In a couple months we’re heading to N Dakota for a week then on to Yellowstone. We’ll be following the Yellowstone on I94 from ND to the park. She’s into rockhounding and I’m hoping to fish while she’s doing that, I’ve mostly fished for bass and crappie in Texas, though I have caught a couple trout on a fly rod before.

Assuming it’s possible to catch anything from the rivers edge on that stretch I’m hoping I can catch a keeper and have it for dinner. But since I’ve almost always released what I catch I’m not sure how to deal with a fish if we’re hours from our destination. Should I put the fish, whole on ice, or clean it near the river?

Any advice or suggestions welcome, thanks