Yeah, I figured that a 1x10 wouldn't be as bad as cross chaining a double, let alone a triple. I'm fine with the 1st and last cassette sprocket being virtually useless...that still gives me 8 gears to safely work with. My only concern was getting the proper chainline and figuring out what type of chainguard I need on the front (although the double chainguard version of the Alfine crankset should take care of this).
You're over thinking this. If you can get within a few millimeters of decent chainline, with either chain guard set up, pick that one. If the roads are at all bumpy, you'll probably want to go with double guides to prevent the chain from dumping in either direction. (that's what I'd do). Otherwise you can install one of those stationary chain keepers that look like front derailleurs.
Probably the biggest difference will be the chainring. Chainrings made for single speed or 1x? don't have shift gates, and are less likely to drop a chain coming from an angle