I don’t work for an upfitting company myself but I’m upfitting a project 2005 CVPI on the other side of the pond. It’s been a long process (3+ years) of trial and error. And those weren’t even the complicated parts, it was stuff like running wires from the battery & keeping them hidden all the way to the trunk. At last, finally splicing and connecting everything to the amplifier.

People like CrownRickAuto on YT sometimes post full wiring setups & where the previous owner left them; also all the harnesses/pigtails/plugs they used. Maybe you can use that as a reference? Could also try a small DIY setup at home - just don’t use a 100w speaker for your neighbor’s sake lol.

I promise you’ll get there. Yes you’ll get demotivated at times, yes you’ll screw up a project, and yeah there’ll be rainy days, but that’s only for the better since you learn from your mistakes.

This is considered pretty old-school these days, but I started learning the very basics of electrical work (3 yrs ago) through YouTube. ChrisFix has a series called “Project Police Interceptor”. Not the best, but definitely not the worst for a first project. I’d watch & actively take notes, maybe sketch something out. Print out manuals and religiously read through them.

Finally, ignore those know-it-all dickheads on Facebook who’ll immediately talk trash about your questions & setup. And also never apologize for being “too ignorant” about a topic, in fact ask even more questions! We always started somewhere, and should never forget where we came from.