I do like having the ability to move a camera anywhere, quickly, without being constrained to a vehicle. What would improve the realism is making Camera #4 simulate a second person. For example, when we need to uncouple... switching to Alt-Camera #4, puts the view point in the 2nd seat. Then we need to get up, exit the Loco, and go uncouple, WHILE still having the ability to operate the Loco. The player then needs to return to the 2nd seat, before changing to normal Camera 4.
