for me, a 45* start would be thin base layer, jersey, vest, arm and knee warmers. Those last 3 can be peeled off if need and can fit in one pocket.
My long ride (more then 4 hrs) check list
3 tubes/ patch kit
4 cliffbars
1 tire lever unless you run wire beed tires.
1 frame pump on the bike or 4-5 Co2 cans
1 small multi tool
1 fully charged IPOD nano
2 bottles (refill stations should be sorta plotted out)
1 meal stop around 50-70 miles into the ride
If you think you are going to run past 5pm, then bring small but bright lighting system and bolt on a rear blinker on the seat post.
You don't need to carry an entire work bench with you, you are just riding a bike. Anything more then what happens to the bike or you is a simple phone call to get picked up. If the pick up is a problem, maybe two 50 mile loops would be a better option.
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Rule #10 // It never gets easier, you just go faster.