I’m starting to run again

I have been getting 1 run in a week, Sundays. My longest was today, 20k. 9 weeks since Sinister and my lower back is still a problem. One spot is constantly tight, it can loosen up during the day but by next morning my hips won’t bend. My wife suggested I run longer than normal, my runs have been 10k, she suggested 20k, in the past the longer I went the looser my back became and less pain. Yup, that did it, after about 15k I could not feel my back at all. I had other pains from not running much, but I stretched those out along the way and finished my run. I think I am back at it, I want to start doing a couple more short runs a week. My plans so far is to do the River Valley Revenge 50k in January. I need to do some serious runs over the winter to keep my conditioning. I am looking at any Ultras in North America that I can run in April, something around 100k 2 months before Sinister. My ultimate goal is Sinister 7 Solo next year. I feel as long as it is not a wet year I can do it in 30 hours. If it is a wet year I can either do what I can and bail early if it is a problem, or just not run it at all and pick another race in August. I need to give that a tink.