The abbey in San Magno makes an excellent place to stay, arriving in Fondi on the next day.
A very attractive option of breaking up the walk differently over the next days is to make a five-day walk (Terracina-San Magno-Itri-Minturno-Sezza Aurunca) rather than following the conventional four-day Via Francigena sequence (Terracina-Fondi-Formia-Sezza Aurunca). This evens out the distances and provides some time to investigate the treasury of interesting sights along the way.
From Terracina the path leada up the hill on Via Anxur and the Strada Panoramica. For a wonderful side trip to the Temple of Jove, there is a path which starts from where the Strada Panoramica makes a sharp left turn. This path winds up the hill to the temple, offering great views of the city, the sea, and the temple grounds. After your visit, the Via Panoramico leads back down the hill to the Via Cimitero, where it meets the path.
After the Temple, the path winds along the coast, offering spectacular views and a great spot for lunch. The route is running over a highway tunnel. There's no sense that the highway is there, except at the very end.
After leaving the sea, the route runs along a hill, a nice path, with continuing great views. Within several kilometers past Terracina, the Lake of Fondi can be seen from the Via Appia, where between it and the mountain (Lautulae Pass) the Romans, in their conquest to the south, were famously defeated by the Samnites in 315 B.C.
The SS7 is an unpleasant walk: too much traffic and too narrow.
San Magno Abbazia is contemporary reconstruction of a monastic complex originally built in the sixth century. Today it houses a very nice pilgrim guest house with kitchen, and we encourage pilgrims to stay.
http://www.oldpaths.global/index.php/maps-and-stages/terracina-to-benevento/8-07-terracina-to-fondi#sigProIdb47d7cb5cb