I've been running just two wheels at the front of the skid for my last 4 sleds now, no scratchers, no issues. I get about 1300 miles from a set of hifax, but I don't ride any trail heavy spots, and if I do ride trail I pull into pow a lot or stop to kick some chunks into the skid every 5 min or so.
I'd take the opposing one off so that you get even wear, it's not like you'll ever just replace ONE hifax, so you might as well even it up.
If this is one of the front wheels, take your mid wheels off, and put one of them up front to match the one that's there. the mid wheels you can do without, not having fronts will eat through hifax QUICK!
This is how I run mine, only wheels I have are on my front shock shaft.