I've done a much shorter route, but still long with a similar amount of preparation - Port Angeles, WA to San Francisco, CA

I can not recommend it highly enough. It took us 2 weeks which is a much more reasonable amount of time to take off. I wasn't really prepped and not in great physical shape, which made it more difficult, but it was so rewarding. That route is very popular and there are hiker / biker camp sites every 30 miles or so. About half the people you see each night are going the same direction as you, so you probably saw them last night.

I would strongly recommend the paper maps from ACA. They are fantastic, and you can get a holder that goes between your handlebars. It's really hard to use your phone as a GPS when you're out of power.

I also broke a spoke on my wheel and it wasn't a very common wheel type. The person I went with had to go 20 miles back to a bike shop and ended up buying me a whole new wheel. So getting bog-standard equipment is very helpful.