Well, I am pretty busy with some other stuff at the moment, so have no time to load OFP do any testing before posting this.
I think that this should little script that I have "knocked up" for you (entirely from memory) should work (within its design limitations):
; camplayer.sqs
; Script to call external camera view of player while player still has control of his movement.
; call the script with:
; [] exec "camplayer.sqs"
; say from a trigger, for example when the player reaches a certain location.
;
; nocam is a a global variable, initialized by setting it to false in your init.sqs, e.g.
; nocam = false
;
; When you want the player to be returned to a normal view,
; use another trigger to set nocam to true, e.g.
; nocam = true
;
; Set the camera to an external view of the player
player switchCamera "EXTERNAL"
; .........................................
#camloop
?nocam : goto "myend"
~0.5
goto "camloop"
; .........................................
#myend
; Set nocam back to false again
nocam = false
~0.5
player switchCamera "INTERNAL"
~0.5
exit
Basically, this should have the effect of turning on an external camera behind the player (like what happens if the player presses one of the keypad number keys... possibly 0, I can't remember?), then when your second trigger fires, the loop is ended and the player is back to a normal view again. Because the global variable nocam is set back to false again, before the script finishes, the same thing will happen again if the player (or whatever) activates the first trigger again.
It may not be what you are looking for (?) and it may be possible to do other tricks too, so sorry if there are any problems with (remembering that I have not tested it!).
PS: I do swith the camera EXTERNAL or INTERNAL (e.g. acting on a plane for example, although it could be a soldier, etc.) during a scripted cutscene for some of the scripts I have done, but I destroy the cutscence camera first, then re-create it again, after the relevant section of external/internal plane view. I have not actually tried to do what you are proposing.