score:8
Tiring, maybe. But consider that there are four of you in a car for 3.5 days, during which you'll be stuck in that metal box for 5-7 hours a day. That's a LOT.
On the flipside, it is only for 3.5 days. I did a trip in South Africa where we drove 7300km (4500miles) in 22 days. It is possible. We took turns, each person being the driver for the day. We took regular breaks. Music, the like to keep us entertained. Good scenery. Animals in the game reserves.
So consider - you drive essentially a full work day each day driving. You're not going to have much time to see places, get out and explore.
Short answer: It's possible. But why not wait until you can spend a bit longer (even a couple of days more) and really enjoy it.
Upvote:5
As this question is getting views lately, I thought of posting an update. It is about 10 years now and I remember this trip vividly.
We couldn't complete it in 3.5 days. as Mark mentioned in his answer, we ended up spending a lot of time towards 'sight seeing' and exploring places. I remember kayaking somewhere and it took almost half day.
In the end, we took the night cruise from Ludington to Manitowoc (C to G in the map). The cruise experience was awesome too.
so, in 3.5 days, we can do a 'half tour' exploring some of the nice places along the route.