If you are not riding locally then...
Eight hours is not incredibly long, but if you are going to be out without a possible service location then a compact plug and patch tire kit and tender style air compressor is always a good idea. And a brick charger to run the compressor so you don't run your battery down filling your tire.
Simple stuff to like an extra CR2032 battery or know your start code and sequence if your FOB dies, a flashlight, some extra bungees or rope if you are carrying anything outside your storage compartments. A few terry towels if you get caught in a heavy rain just to take moisture off your dash areas.
If you are riding backroads and not interstate an old fashioned road atlas is good to have. A backpacker tarp with stuff sack if rain is predicted so if you need to pull over you can make some shelter for your self and for your bike. That is heavy downpour type thinking, but trust me it comes in handy. Been there done that.
Warm gloves and light weight gloves. One extra pair of daytime riding glasses and one extra pair of night time clear glasses.
But mostly check your predicted weather patterns from start to destination and you decide...
But I am assuming you are riding 8 hours into places unknown. If it is an 8 hour journey to sisters house in the same state. No big deal. You know where to get everything you need if something happens.
