340 mile long Central Missouri Bike "Race" / Ride

I am foolishly contemplating the idea of partaking in this event, not as a 'race' per se, but as a ride. I've two Specialized bikes, first is Roubaix Elite, and second is TriCross Comp. Tires that are currently on the bikes are not conducive to this ride, so I appreciate your suggestions for which bike, and all related gear, and preparation / training.

If I wanted to partake in this 340 mile long ride, that has elevation changes of +20,694 ft / -20,693 ft [but note that "the elevation feet are a lie. It is much hillier"], and is upon mix of paved [167 miles] and unpaved [174 miles] surfaces, what would you recommend, in regards to gear, tires, what to take with me spare parts etc., camping supplies, lights, etc.

https://www.bikereg.com/central-mo-circuit and here is the route https://ridewithgps.com/routes/49188146

Many of the elevation gains (climbs) are 3-4%, steepest is 5%... and majority of the descents are 3-5%, with some in the 5.5-7%. Thoughts, suggestions? Am I foolish 62yo male (overall good health, walk ~10k steps per day, even winter) idiot for even thinking of this extremely challenging endeavor, especially as I've not done anything similar to this... I've only rode ~100-130 miles a few times, never overnight camping and having all my supplies with me. My typical rides are in the 30-60 mile range, here and there.

Talk me out of this madness! lol