I didn't have a rigorous training plan for my SF to LA tour, but I did train.

Before I started touring, I was riding 4-6 days/week. 3-5 times during the work week, I'd ride through my lunch hour. Most rides were on my road bike, generally a 15 mile flat course riding as hard as I possibly could (~17.5mph average). Once or twice a week, if I was lucky, I'd manage to do a 45-minute lunch ride on my mountain bike. Probably about half the distance, but with a good 800-1000 ft. of elevation gain. Weekends, I'd concentrate on longer (2-5hr) rides with a few more hills (2000-3000 ft.). Weekend rides were generally done at an "all day" pace (~15mph). I eventually worked up to the point where I could do two back-to-back days of ~60 miles with 3000 ft of elevation gain/day at an average 15mph and still feel fresh at the end of each ride.

6-8 weeks before my tour, I finally had my touring bike built and all of my luggage available. I started riding the touring bike exclusively at that point. Initially, I mounted the luggage and packed about half my gear. Backed off on speed and distance a bit, but tried to maintain the same general level of intensity. After a week or two, I started carrying 90% of my gear on the majority of my training rides. Figured I needed the time to get used to riding a bike that was 3X heavier than my road bike. Had to back off the distance again, but slowly started working back toward longer rides. Got to the point where I could do a 60-mile day with 3000ft of elevation at an average of 15mph followed by a 40-50 mile day with 1800ft of elevation at the same pace.

At that point, I figured I was ready to go. My plan averaged around 70-miles/day with a max of 3000ft of elevation gain and the longest day was 90 miles and around 2000 ft of elevation gain. Figured that with 9 or 10 hours of daylight available, my speed could drop to a leisurely 10mph and I'd still make the distance.