Just skip the booze, in preparation and on the ride. It will only slow you down!
I would not do that event on that touring truck. No way. I have that type of steel touring bike for commuting and know how much slower it is than my classic road bike.
120 miles should be doable on day one. Just pace your effort, some people use a HR monitor and stay under a certain HR threshold. And I agree, you can start with your buddy but in the end it is better to go your own pace unless you have a closely matched partner. It is a supported event, so it isn't like a hike in the wilderness where you need to cover for each other. I dropped my buddy on the Death Ride a couple years ago because I was worried about running out of time. Which is exactly what he ended up doing.
Keep us posted. It sounds like a challenging event. It is great to plan on something to have to train for. You'll train a lot harder knowing you have to get fit!
G