I did it last year, so here are my thoughts:
Totally doable on a road bike. Gravel/CX bike is overkill unless you want to be extra comfy on the rocky sections, but you'll pay during the 90+ paved miles. Tubeless is probably a good idea. I did fine on a Tarmac Disc with 28s, and was held back mostly by lack of skill. I hit the dirt section probably in 30th position or so, but I quickly lost ground due to lack of skills (I was passed by many with skinner tires than mine, a teammate that I did the recon ride with was on 25mm gatorskins and consistently pulled away from me in the dirt so I just suck at dirt). There are a few sandy/loose sections. Some of the sand pits are quite deep. The black cyn descent was, for me, quite scary. I'd start losing traction in the corners, but others were going a good 5 mph faster than me, so again a testament to my wimpiness.
Last edited by wktmeow; 02-11-20 at 08:22 PM.