You can get long shank bits to access those fiddly bits. I ordered a heap from the states. It was cheaper buying new ones than paying to get them properly sharpened.
They're not as easy to sharpen yourself as a standard drill bit.
I think I was paying about $15 each for standard shank length and $25 for long shank.

I have limited search capacity at work but this is what I used (Bought it from local mob in Aus - gasweld I think).
Spot weld drill bit
I used it to remove both sills and front valance on my coupe.
Things to note when using any version (and why I chose this one in particular).
When starting, the bit tends to wander on the surface, but once you start it should work pretty well.
To combat this using the above bit, I drilled a hole all the way though the spot weld to enable the centre spike to sit on the hole. This seemed to stop the majority of the bit wander issues and wasn't too hard to tac closed the small hole when the panel was removed.
Second thing I liked about this bit was you can buy replacement bits and the centre spike can be removed and resharpend.

Hope that helps.


Bryan