Thank you for the detailed information, but I can't locate any companies that offer tours that depart throughout the day.
Kosmojin - 8:00-15:00
Koridoor - no JSA only tour, only joint DMZ
Korea Travel Easy - DMZ only
Trazy - 9:30-15:30 (Tu-Fri only), but a lot of "fluff" like taking an extended lunch
I may rake the Trazy one only because it at least leaves later in the morning.
Thanks again!