A compact instrumented downhole coupling that includes a carrier and a set of sensors and electronics that are installed within the carrier. The carrier is a tubular structure having couplings at each end and a bore therethrough, where cavities are formed in the carrier wall. The cavities are open to a side facing away from the carrier's bore, where sensors placed in the cavities are accessible through the side opening. Electrical connections to the sensors are made via the side opening, and a clamp can be installed in the cavities via the side opening, the clamp holding the sensors securely in position within the cavities. After installation of the sensors in the cavities, plates are welded over the side opening to form an enclosure for the sensors in the carrier wall.