Hi... I think as an optional extra you could get something called the 'cab centre locker seat' which sat in between the 2 front seats to allow a third person to sit in the front... It could then also be pushed back to give an extra seat at the table. You dont tend to see many around but they are out there... Probably will get it custom built if I can get measurements.
Anyway the light sounds good... What sort of condition is it in?? Have you got any pictures?? Also when you say this would have come out of an early devon what sort of year approx.?