You've got the picture, Walt! The actual compression pressure will be highest with the stock cam, as it closes the intake valve sooner on the compression stroke and there's more volume to compress. An RV cam usually makes only a slight increase in duration, but it has a higher lift to allow for longer useful open time of the valves. RV cams generally develop lots more low-end torque than stock cams, without making much of a change in the top-end horsepower. If you want a stump-pulling off road engine, or you're hauling heavy loads on the highway, the RV cam is the way to go.
Jerry