You all are making this way too difficult. If you want to do it yourself, go purchase some shark bite fittings for the size pipe in question. Abandon the old wheel handle gate valve, install a sb coupling and penetrate the floor. Install a sb ball valve, 90, 90 and back through the floor and reconnect to the existing downstream line. You will need shark bite fittings and less than ten feet of pipe. A couple of trips in the crawl space and you are done.