For what it's worth here's some pictures of my finished switchcraft plug-based solution. (Be careful when ordering; the Mouser website incorrectly listed some female connectors as male and vice-versa... really check the EXACT switchcraft connector that you're ordering.)
I used the StillDragon TC element cover option and a short length of 10/4 wire (DON'T use 10/4 wire; use 10/3 -trust me on this) connected to a Female Switchcraft Fast-on cord connector (50amp rated version). Then I made a 9-10 ft 10/4 cable with a male Switchcraft Fast-On cord connector and this will connect from my control panel (which has a female control panel Switchcraft Fast-on connector) to my electric element.
I really, REALLY love this setup. I don't have any long cables hanging off of my HLT or kettle, I can quickly and easily remove the elements to scrub them if necessary, I can quickly and easily get access to the electrical connections if necessary, the whole thing is grounded end-to-end (fully tested), and it looks and functions great. I also don't have to worry about the cable twisting and unplugging itself (rare but possible with twist lock); it's also quite water resistant (esp with some strategically placed beads of clear silicone). The plugs are also super cheap compared to the alternatives.
1. Wiring the Switch Craft fast-on cord connectors is TOUGH -it is very hard to make the blade connections inside the connector because if they're long enough that you can actually install them with your hands/ a screwdriver you're going to have the cable sheath sticking out and you're DEFINITELY going to have to use heat shrink wrap; the alternative is to cut the wires very short (very small margin of error with these things), align them perfectly and then just push down really really hard and hope that they all went on correctly. (and of course test with a multi meter to confirm.) It took me hours and hours and a bunch of ruined blade connectors to figure out the right internal wire length.
2. Safety Concern
The StillDragon TC element kits come with pure copper "blade" wire connectors without any external insulation on them-this includes for the two hot wires. They do come with shrink wrap but on my elements just fitting the TC over the finished wires rubbed through the heat shrink stuff enough that both hot wires were making an electrical connection with the TC itself- when I was testing the grounds with my multimeter I noticed that both of the hot wires AND the ground were "grounded" to the TC connector and then took it apart and confirmed my suspicions. (This was after bending the blade connectors at an almost 90 degree angle.) Everyone should be buying insulated blades for the two hot legs and I'd say some heat shrink tubing over that to connect the hot wires. I really have to completely recommend against using the included copper connectors.
Picture of one finished element with Switch Craft Fast-On "Pig Tail" solution:
(If anyone else has done this yet, I certainly haven't seen it.)
Here's a close-up of the SwitchCraft connector:
Here's the two elements and power cable all in a single shot:
I'm considering using another set of SwitchCraft connectors to go from my spa panel box to my control panel box (I'll just switch the male and female ends around there so that my power-in and power-out plugs are different) but they're honestly so much work to wire and I just want to make beer so I might just go with a twist-lock there...
I seriously don't think there's a solution out there that I'd be happier with over all. The connectors are frustrating to wire and the StillDragon elements DO require getting a TC ferrule welded into your tank (which has been a multi-week ordeal for me so far with my flakey welder) but it looks drop-dead gorgeous, is very reasonably priced, super functional, should last basically forever, and with the aforementioned replacement of the copper blade connectors (and of course GFI protection), is incredibly safe.