How to fix a 1 ft separation in a tent seam?

I recently received a truck-bed tent from a fellow TW member. Looks mostly good, but there is a 1 ft stretch where the wall meets the bottom that is separated and open.

I know there must be several possible solutions ... "Alien Draft Seal" (that obnoxious guy), Super Glue ... almost anything but re-stitching because there is no path I can see that will sew the two sections together.

I know I can "try the supposedly weather resistant tape" first or test with SuperGlue, but the glue can melt and the tape may just also remove the chance for another option.

Any ideas before I try something that prevent further good attempts?

 

Why can’t a patch be sewn in?

 

Need pics. Was it stitched previously?

 

I've had the same patch of Gear Aid Tenacious Tape on the cuff of my ski pants for about three seasons.
Repair Patches for Jackets and Outdoor Gear | GEAR AID

 

^ This. Will vouch for Tenacious Tape. Used it to reattach a boot sole backpacking. Got us back to the trailhead no problem. Good stuff.

 

Previously stitched. Person said they pulled too hard on that corner and took off the hold down strap, but may have done more, Sits outside the truck bed folded over the side so less chance of water invasion, but still.

 

Fixed it, I think. Time will tell ... https://www.tacomaworld.com/threads/i-fixed-the-bed-tent-that-was-free.825826/