You should be able to drill new holes and run them that way I would think. I actually did this to a econo van when I needed a extra seat. Got a captains chair from a Conversion Van and installed it seat belt system and all behind the drivers seat.
Honestly the rear captains chairs for the EX suck. They are nothing like the front. I would for sure want to run front seats with no sliding at all before going with the proper rear seats.
I had always thought it would be cool one day once the kids are old enough to have their own trucks to get rid of all the rear bench rows and go with front captians in the second row and if possible even the third row and if not go with stock second row stock EX captains for the rear. The only reason I have not looked further into it is so I have room for a few more bodies as we are already 5. Add in some of their friends or a relative and we would be full with just one extra. Capacity of 6 instead of the current 8.