revelate designs viscacha seat bag (pica if you'e really UL)
light weight down bag like this (get summer weight one if you're really UL)
tent like this or
bivvy like this (if you're really UL)
sleeping pad like this (get the small if you're really UL)
toothbrush, phone, spare tire & repair kit
Ride the lightest bike you own at least 60 miles (100+ if you're really UL) camp-out one night and ride back.
Then you'll be able to evaluate if you need more.