Group of Bikes: Is 3x1 an option?
I don't think you can make a 3x1 setup work.

In order to have the chain change gears, there needs to be a mechanism to take up the slack in the chain. In a normal dual-derailer setup, the rear derailer does that.

You might be able to make it work with a chain tensioner, but I'm not sure if you can find one with enough range to do the job as well as a rear derailer.

Obviously you could do it with a rear derailer locked to the one gear, but that defeats the entire point.

A 1x8 or 1x9 would work fine, of course, since the only derailer is a rear derailer and it would handle the tension.

Another option would be to go with an internally geared hub (IGH). It's fairly common for "cruiser" and "town" bikes to have a 3-speed internally geared hub. That would give you most of the extra durability of a singlespeed drivetrain and allow for a very thorough chain guard (no pant rolling needed). Internally geared hubs often have a built in coaster brake, which would mean you'd only need a front brake. Even better would be a belt-driven internally-geared-hub bike (no chain lube!), but that requires a frame (at least dropout) built for it and would definitely be more expensive.