Fixing rear-wheel puncture on belt-drive bike
It looks good except I think you will have to loosen the tensioner. You won't have to spread the frame. When the recessed allen head bolts are removed you risk damage to the very end of the threads due to the belt tension. It is unlikely you can reinstall the tensioning assembly with tension on the belt. Due to the complexity of this kind of flat repair you may want to consider some type of puncture prevention be it tires, tire liners etc. I have used a technique of repairing a puncture without removing the wheel. In this case a rider on my local trail had a flat, bolt-on wheels, and no wrench.  You flip the bike upside down. Work one edge of the tire off the rim. Pull out the tube and patch and replace as usual.  Instead of working your hands around the wheel you spin the wheel as you work your way around. It appears in the photo that you may not have to remove the shifter cable. There may be enough slack to work it around the frame and effect the repair.