I do not know and have not been and cannot find Sierra del Abra but here is another place you might like to visit - you can boondock in the parking lot at the reserve. You can find it and plan a route on S&T. Near GPS 19.587856 -100.267874 . We have heard the places in Church book may be closed but there may be a new campground between Ocampo and the reserve.
http://en.wikipedia.org/wiki/Monarch_Butterfly_Biosphere_Reserve
http://mariposamonarca.semarnat.gob.mx/
Also, west of Guanajuato I think called Cristo Rey on Cerro del Cubilete where you can see for miles - the statue can be seen from Guanajuato.
http://es.wikipedia.org/wiki/Cerro_del_Cubilete
http://www.visitmexico.com/en/historic-monuments-in-guanajuato-mexico
So much to do - so little time.