Tires for Barry

I think those will be just fine. I did it one year no problem on some 33mm Bontrager CX0 tires so you could go narrower if you wanted. 

Last year, the 95% of the surface was like someone put a thin, hard layer of sand over  asphalt. 4% was sand filled potholes. 1% was the sanddune called Segar Rd, that you have to run up because the guy in front of  you was on 28mm tires or fell. Overall, the surface is pretty forgiving or the wrong tire, though the winners use fat slicks. If you're running knobs, maybe bring a scarf in case you get sand fling.
You can see the typical road here: https://www.instagram.com/barryroubaix1/?utm_source=ig_embed
I had a fat bike behind me and a guy on 28mm in front of me. When you hit a 1/2 deep sand spot, it was pretty astonishing how quickly the 28mm road tire slowed an the guy on the fat bike closed in on you. Most everyone was on CX tires.

I used 43mm GK SK at 38psi-ish, which were pretty good, but I'd say you can get away with a smooth tire if you want and there's no need to tire for the soft sand because the crowd will dictate that you can't really ride up it.  I'll be using a 38mm GK SK this year or might mount the 43mm if it's going to be wet.

I did the 100 miler last year on kenda flintridge pros 40mm in 6 hours. I would sacrifice some watts to have the wider tires in the unmaintained sections and  extra cushion when that blind pothole the guy your drafting didnt tell you about. 

what did you end up using for tires? I did the 100 miler in just under 6 hours. Using kenda flintridge pro 40c tires. Made one mistake though, I had a 1x11 setup. With a 46t in the front and 11-42 rear. Definitely need a smaller ring up front for that amount of climbing.