Keeping minnows alive question

I will be at a lake for a week with my boat in the water. I bought a used boat that has a live well with a bait bucket section as part of the live well. Which option do you think will keep minnows alive the longest (Park Rapids, MN in July if that is relevant)

1. live well when on the boat, but when docked let the bait bucket float next to the boat

2. keep transferring them and put them in the fridge when not fishing

3. keep them in a cooler and swap water daily and put in some cool packs to reduce the temp.

Also, what's a reasonable expectation for how long they'll last.