As stated in the previous threads, as long as you abide by the rules and regs for boating and diving, you can pretty much get in your boat and dive most anywhere at PK.
I have been taking my boat out there for years and dive all over the lake. Just make sure you abide by the laws and use some common sense as well. (Like don't dive in the middles of a busy boating area, even if you are legal, it just pisses people off and is dangerous)
So if you go out to hells's gate, just make sure to tie off/anchor on the lake side of the shore or island away from the boat channels. (your still within 150ft of the shoreline) And keep someone in the boat at all times, just in case. Definitely pull a flag. It is pretty cool wall dive when the conditions are right.
Randy