How much should I offer?

[fossyant]

The dent is probably fine, steel is quite resilient stuff, not like that plastic stuff !

 

[marzjennings]

I was going to be replacing the standard QR skewer with an internal cam skewer, would it make sense just to find a proper axle to use with track nuts instead?

If the QR holds then you're good. Try it first and if you find the wheel shifting then look at track nuts and solid axle.

 

[HovR]

There's no reason why a quality QR skewer shouldn't work with the horizontal dropouts. I currently own two horizontal dropout bikes with internal cam QR skewers and they've never slipped. In the past, hundreds of models of bikes used QR skewers before the invention of vertical dropouts with no issue.

You do have to ensure that you're tightening them up properly though - almost as tight as you can physically close it.