a couple years back , they had graded the road a week before. And half the field was getting flat tires. And certain sections do have bigger rocks. If you use the 28's , fill the tires to full capacity. You won't  be comfortable,  but you run a lower risk o pinch flats. The ride is also notorious for foul weather, and in that case do the 35's If you can do the 32's that would be cool, but run more pressure. Or carry a bunch of extra tubes

So, I did year one on a road bike with road bike tires and gearing.  Not ideal.  It's nice to have the lower cross bike gearing and the wider tires become more of a benefit the wetter it is.

No worries about the brakes.  You can actually finish the race without having any.. :/

I did this race last year. The roads up there turn real soupy peanut butter like when wet for whatever reason. I would suggest you pay attention online for updates on road conditions leading into the race. They usually provide updates on Facebook. I did the race on my mountain bike because I don't have a cross bike and I ended up glad I did. About half way to a third of the way through the road conditions went south and I was very glad to be on a mountain bike at that point. I passed a man and woman at the top of a climb, both of them on cross bikes. The woman looked like she was close to crying if she wasn't already. They were stopped and she was trying to decide if she could make the descent or not. Looking down the road it was indeed a soupy mess. I asked the man if they needed help and he indicated that they would figure it out and I should keep going so I did. The descent was indeed sloppy and I was fish tailing even on mtb tires. I didn't see the couple again so I'm not sure what they ended up doing. If I remember correctly I was on maxxis ikon tires. Just my opinion based on my personal experience and gravel riding abilities.

After the rain i decided to ride the cross bike with the 35mm happy mediums, 46/34 up front. just glad it wont be raining at the start!