You can cover-up that nadir in your equirectangular panorama without using complicated scripts, by following these easy steps. I'm using Photoshop to create a mirror ball nadir cap, but any image editor that supports layers can be used to produce this effect.
Step 1 - Duplicate Layer
Duplicate to new layer
Start with an equirectangular image, duplicate it to a new layer and make the layer active.
Step 2 - Place a Guide
Insert guide above tripod
Place a guide just above your tripod on the top layer
Step 3 - Select Area
Select area above guide
Select the area above the guide with the marquee tool
Step 4 - Transform
Drag top to bottom
Use the "Free Transform" tool to create your tripod cap by selecting the top-center marquee handle and dragging it all the way to the bottom of your image.
Apply, and you're done. If you place text just below the guide it will appear around the edge of your tripod cap.