Good info. I've done five 50k's now, but it's been a few years. The big unknown is how my body will respond to the longer distances.
I'm around a 30 mile/week base right now. Looking to ramp that up. I have a 24 mile trail run I'm signed up for in September, then a 50k in April, a 100k in June, and the 100 miler next August. The 50k, 100k, and 100 miler are considered the triple crown of PA trail running.
I live in Northcentral PA where all these races take place, so I can run those trails on weekends within reason. My daily training is right from my driveway down the road and up onto state gamelands. I can get an out and back of 5 miles with 1,000' of gain. I just repeat sections or the whole thing for more mileage or elevation as needed.
I read the book Training for the Uphill Athlete the other month. Been really focused on building the engine with zone 1/zone 2 training.