On my last Suburban (97) I looked at going from barn doors to a tailgate, IMO a tailgate offers a better rear view for backing a trailer. I abandoned this project due to the possibility of totally screwing things up real quick.
The structural support is already built into the door frame, and most of the fasteners are tacked into place behind the panels. The biggest problem is door alignment, you have to be pretty precise with your measurements to get the lines to match-up and everything closing and latching correctly.
I'd say it's possible to do but may take a little trial and error fitting to get it right.