You just need a little creativity. Each rod should be attached to your wrist by a rope, and have a wooden plank suspended about 3 feet underneath, like a kid's swing.
1. Affix Rod #1 six feet in the air.
2. Stand on the plank under Rod #1, holding onto the rod for balance. You are now three feet off the ground.
3. Affix Rod #2 at eye level; if you're six feet tall, this is nine feet in the air.
4. Grab hold of Rod #2, and climb onto its plank. You are now six feet off the ground.
5. With your toe, push the button on Rod #1. It falls and is caught by the rope on your wrist.
6. Reel in Rod #1.
7. Continue this process. It's slow but requires neither extraordinary strength nor extraordinary balance. If you do fall, one of the ropes on your wrists will catch you.
What I don't understand is why I should care about the PCs being able to do something that most spellcasters can pull off starting at 5th level or so. I long ago learned that you can't expect vertical terrain to stop a D&D party once they get past the low levels. Sure, you can climb into the sky if you like. What do you plan to do when you get there?
Drop the polymorphed Dragon I am holding in my bag. Or, if you allow the mammoth trick, do that. Or start going sideways, and see what new world I can reach after a while like this.