Old Spanish Trail...

I have been reviewing some maps that are online and so far I narrowed it down to where the Spanish Trail comes out of New Castle down through Enterprise down to St. George and on. From what I gather the Santa Clara River comes out of Pine Valley through Central then winds on down through Gunlock Res. and past the Paiute Indian Reservation and finally turns southeast towards St. George and dumps into the Virgin River. The Spanish Trail just keeps going straight through the Paiute Indian Reservation and keeps going south. So that means the Santa Clara River and the Spanish Trail Follows each other from outside of Central, UT and they go through Gunlock Res. and down to the Paiute Indian Reservation before they split and go different directions. I'm guessing that wherever the road leads by Central down to (hopefully before) the Paiute Indian Reservation is where I would want to do my search. I am probably going to need to do more research because one source say's that the road this prospector was taking was headed towards the west over utah hill and says that he crossed the Santa Clara River at some point. The best part is that the more I research and study the more I learn my history:) .