II would (but this is just me)
A yard of concrete in a four foot deep hole basing each four inch square tubing gate post, a tractor supply gate covered with your existing wood, anchors eight feet back from the posts and cables to the top of the post.
I am NEVER about taking the harshest and most labor intensive route. Except on gates. Given a chance, they will jack with me every time I take less than a stupid amount of overkill.
Or, if you don't use it and the floppy nature and the Malalingment and lifting and trying to latch, of what you have and the inevitable post failure is farther out than you care:
That wheel will have to roll Somewhere and it sure won't like high grass or snow or mud or you leveraging the top of that gate while it's fighting you from the bottom. And the entire track of that wheel has to be within an inch of level or it will wobble your gate post so loose it will render the gate unusable in just a few openings. 8feet of gate puts a lot of footpounds of torque and lift on a post when the gate is trying to lift itself 6 inches to compensate for a grade.
Your wheel is a major part of your problem. If you put 20pounds of pull/wheel resistance on that gate...
20 pounds times eight feet is 160ftlbs of torque going somewhere(actually it might be the eight foot length added to the height of your push for a squat load more). Real posts and no wheel eliminate that.
