Might even end up drilling a hole in the top of my TJ07 for a Fill Port..or something but I'd need some courage to do that...
If you do, you probably want to get a step drill. Centre punch where you want it, drill a smallish hole with a decent HSS drill and then widen it with a step drill. If you were to get a large HSS drill and do it, you'd likely end up with a triangular hole. Guess how I know!
You can pick up a step drill for around a tenner IIRC from various online sources as well as trade - focused (but open to the public) tool suppliers.
X584EVA: Enjoy. Lots of info in this thread. Plug your cables in before you mount in a 5.25" bay or have colourful language on standby!