Which bike should I take with me?
If you want something universal, an MTB with fork suspension is a great choice. MTB with a solid fork is the best choice for skilled riders who can withstand the pain caused by concussions. The pain hits the palms of hands, wrists, forearms, shoulders, and neck the most. GRAVEL bike is a great choice for those, who are skilled riders and accept slower tempo and pain in rough terrain, but prefer flying through the more flat parts of the track. If you want some thrill going downhill, or your joints, bones, or spine would get too painful during a long race, a bike with full suspension is the best choice. Individuals, who will view it as just a ride-along opportunity can take a fatbike, recumbent bike, tandem bike, one-wheeler, scooter, or just walk. Masochists can take a cyclo-cross bike at the cost of great suffering during the race.
Was this information not enough? Have a look at the Bikepacking methodology by Štěpán Stránský, which is a gradually updated wellspring of information about the gear, preparation process, and philosophy and principles of bikepacking.