Just to give you confidence about your trip. This is a post from a friend of mine
Kids are capable of doing amazing things, if only given the opportunity.

"The plan was for me to bike from Shorewood, WI to Madison, WI with three grandkids, ages 8,6 and barely 5. 90+ miles. But then, a small complication: our 3 yo grandson wanted to join the convoy on his 14" two wheeler. I didn't have the heart to refuse his attempt, especially since almost all of the route was off-road, and he'd been riding for about a year, having already done at least one 20+ miler this summer..

The 3 yo finally cashed it between mile 59-60 on day 2, due to emotional fatigue and nap deprivation, and also being tired of all the gravel on the Glacial Drumlin Trail.

The other three grandkids made it all the way, 92 miles or so.

But making it all the way - the ostensible goal - was less important than the other lessons they learned: 1) Supporting each other 2) Consoling the youngest when he had his predictable meltdown 3) Consoling each other when they had their inevitable meltdowns 4) Being comfortable with hard, sweaty, persistent effort 5) Weathering deer flies 6) Weathering boredom 7) Learning to enjoy "Type 2 Fun" (not fun while doing an activity, but fun in retrospect) because life can't be all "Type 1 Fun" (fun while doing an activity). -8) Learning how to fall off a bike, cry, then climb back on. Which was repeated far more often than I could have predicted.

And I discovered that kids can do amazing things: 1) Manage to somehow fall off of a picnic seat during an uncomplicated lunch. Multiple times. The 3 yo did it twice, the 5 yo once. 2) Recite an incredible diversity of clever songs - all about poop or other bodily emissions. 3) Scarf down an incredible amount of calories that would lead to you or I gaining at least 5# each day, but for them...the calories just miraculously vanish 4) Talk, jabber, and ask enough questions non-stop to drive any adult insane, no matter how emotionally resilient 5) oh, and also expend a mind-boggling amount of energy and go the distance, merely on the flimsy premise of an ice cream cone at the end."