You should really check on TheElectricBrewery.com to see how Kal rolled his 1/2" Stainless. He did a great job using zip ties and very little pressure on the tubing. Another suggestion is sand, but sand can be hard to fill and clean out. One thing I haven't tried but would really like to try is filling the coil with water, freezing, and attempting the same kind of technique as Kal and the gang. Freezing would provide a good resistance to kinking as the ice would crack and crush similar to sand, but much easier clean out. It is very possible to do it without sand or ice, as you'll see in other examples.
The other aspect of the permanent IC in your BK is the cleaning aspect. You have to consider that it may be significantly harder to clean a coil when it's attached inside the kettle. The convenience of easily removing the coil to clean can't be ignored. Also you reduce your stir space in your boil kettle, which may not be a big deal if you're not using extracts.
Here is my coil installed in my HLT. The reason I chose to go permanent was because it will only be submerged in hot water, so cleaning should be a breeze.
This was apre-coiled 3/8" SS immersion chiller from Amazon (NYBREWSUPPLY). I made clean cuts at the top and bottom bends to get rid of the immersion risers. Then used 90 degree compression fittings. NOTE: If I was doing this over I would definitely go with 1/2" tubing, and the 3/8" causes significant head pressure on the March pumps, greatly reducing flow rates.