Wiring New Lights

For context: I do not have much electrical experience outside of a classroom, particularly when it comes to vehicles. I am about to take a 4000 mile camping trip around the Grand Canyon this summer and one of the things I am doing to my truck for this trip is adding exterior lights to make my life easier (and because it looks cool, duh). As stated before, I do not have much practical electrical experience and I just wanted someone else to look over my plan and double check that there are no other considerations or mistakes that I have made/missed. Thanks in advance for any help or guidance. On the plan I did overestimate the length on purpose, rather be safe than sorry, and I am leaning towards using 14 AWG for all the lights (unless that would have any negative side effects) and an 8 gauge for connecting the battery. I am also curious if the light has a say 18 or 16 gauge wire coming out of it can I splice a larger wire directly into that or would I have to modify the light? Like I said before, assume I know nothing about anything.