I saw a quote of C37 range of 550 miles. Hammond to Garland is about 470 miles. However I have seen nothing to suggest the C37 could carry more than pilot and co-pilot.
Colin, according to Wiki. the C37 could carry four people.
General characteristics
Crew: 1
Capacity: 3 passengers
Length: 24 ft 10 in (7.57 m)
Wingspan: 33 ft 10 in (10.31 m)
Height: 7 ft 3 in (2.21 m)
Wing area: 180 sq ft (17 m2)
Empty weight: 1,300 lb (590 kg)
Gross weight: 2,220 lb (1,007 kg)
Fuel capacity: 35 US gal (29 imp gal; 130 L)
Powerplant: 1 ? Warner Super Scarab 7-cylinder radial engine, 145 hp (108 kW)