Security wheel skewers for front facing horizontal dropouts
This may be too late (just joined StackExchange), but the reason that Pitlock does not recommend using their skewers in any horizontal type dropout is in the configuration of washers between the &quot;cup&quot; of the rotating end, and the Pit inside the &quot;cup&quot;.
Please refer to the photograph below; all numbers begin from the left side of the image.

The toothed washer (3rd) grips the hex flats on the end cap (6th), which passes through both the cup (5th) and the nylon washer (4th). If the Pit (2nd) is torqued down too much, it can cause the toothed washer to deform to the point where it no longer grips the end cap. It can also dig too deeply through the nylon washer and eventually secure some purchase against the cup. This would allow a would-be thief to be able to grip the cup with some sort of pliers and potentially loosen the Pit.
To avoid this (and this is not common, but any locking skewer only works correctly if used correctly), Pitlock does not recommend any torque on their skewers above 10Nm. A wheel held at this torque in a horizontal or semi-horizontal dropout, under heavy load, has a much higher chance of slipping. They also recommend replacement of the toothed/nylon washers over time to avert this.
You can over-clamp a skewer to avoid this. If you still want security skewers, I would go with Delta locking skewers, and white-glue a ball bearing into the 5mm hex head opening. You can torque them down to your heart's desire, and still have a good measure of security.
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