Four days out, and you have seen all of it
The advantage of a small region is that you always sleep in the same place.
From a campsite on the coast any point in Molise is under two hours away, and almost all of it is within one. So it is worth leaving the base where it is and making day trips: one towards the Samnites, one into upper Molise, one into the mountains and one out to sea.
Sepino and the Samnites
From Termoli you drive up the Bifernina to Campobasso and from there down to Sepino, where Saepinum stands: a small and almost complete Roman town, with its walls, four gates, forum, theatre and basilica, set in a meadow and with a few farmhouses still inside it. Entry is free and you walk around as you please, which in Italy does not happen often.

Pietrabbondante and upper Molise
Further north, at nine hundred metres, stands the Samnite sanctuary of Pietrabbondante: a theatre from the second century BC with stone seats shaped to fit the back and, behind it, the remains of two temples. It looks out over a whole valley. The same day takes in Agnone, with the bell foundry that has been working since the Middle Ages, and the reserves of Collemeluccio and Montedimezzo.
The Matese
You climb from Bojano or from Campobasso up to Lake Matese and Campitello. In summer you walk towards Monte Miletto and across the pastures above the lake; in winter it is the region's only ski resort. The road is long but not difficult, and the climb from the coast is two thousand metres in a little over an hour and a half.
The Tremiti
In summer the hydrofoils for the Tremiti islands leave from Termoli: fifty minutes' crossing, and the day is done without taking the car, which is of no use on the islands and mostly cannot be landed there anyway. The Tremiti are in Puglia, not in Molise, but Termoli is the handiest port for reaching them.