I have a Windsor Timeline, and I was given a freehub rear wheel that I converted to single speed so I can have a quick way to change from the 700x32 that come with the bike, to a 700x25 depending on my ride that day. The wheel set that I converted is a quick release, and I am worried about it slipping when I am cranking up a bridge (Florida Mountains). I took it for a quick test drive around the neighborhood and had it slip a few times on me.

Do I need to just crank down on it super hard, or can I just put a bmx chain tensioner on it? The thing that worries me about the chain tensioner is the fact that the only part sticking out past the drop outs is the skinny little skewer, which worries me putting much force on that.

The best solution is to get a high quality quick release skewer.

get a closed cam QR, like the ones shimano or campy sell.
if your dropouts are chromed, you'll want it slightly tighter than usual.

it's not like a SS or FG exerts any more torque onto the QR than a geared bike does and QRs and horizontal dropouts have coexisted for a long time now.

You can try putting some serrated crown washers between the QR and the dropout to enhance grip. You'll probably get some slipping, though, if you mash hard.

PS: You don't need to use a separate tensioner.

Ok thanks. Ill tighten it up pretty good tomorrow and take it for a test drive. Lol, last thing I need is to be the ******bag that someone has to stop for on a group ride because I dont know how to keep my bike rideable!