You won't be able to cover over the metal rod, but you can cover the area underneath. Cut a small strip of covering and slide it in behind the rod, and then fold it over the top and bottom of the horizontal stabilizer. Then use your covering iron to secure that portion that went over the stab. You can use the tip of the iron and seal down the bit of covering you can get to above and below the rod. This will be more than enough to seal this area.

As hindsight areas such as this should be covered before installing the elevators.

Hope this helps

Ken