Head lite removal

Most of the new headlights have a bulb assembly that plugs in from the rear. That bulb should have a gasket to prevent water from getting in to the light. I would check the gasket and see that it is present and find out why it is not sealing properly. If the other headlight is dry, that indicates that the design is fine but one headlight is not sealed properly. Drilling a hole does not fix the problem. Check the gasket to find the problem.

You can take a very small drill bit slightly larger than toothpick drill as low as you can and let the water drip out. Clean the hole with a toothpick until the water is gone. You can then use canned air, or an air compressor on a low setting to dry the interior. Most newer Riggs use headlight assemblies from a major manufacturer and make the cap to fit the light. If you can find who they used they are easy to find and cheap on ebay or Amazon. Im not familiar with your rigg but it's usually straight forward. Pull the power to the light it's usually clip type fitting with a release tab. Should be 4 to six screws or bolts holding the lamp assembly in place. It may come out the front or back.
Hope this helps.
Jw