Wheel width difference potential adverse effects

The four primary wheels on this truck are 15×7 steel wheels with chrome wheel skins. The wheel for the spare tire, however, is a 15×6 basic steel wheel. Attached are pictures of both wheel types. All wheels including the spare are mounted with 225/70R15 size tires.

Due to one of the four primary wheels having been damaged and no longer usable, my question is as to if there could be any potential adverse effects in running the spare as a permanent replacement in light of that the wheel is 1" narrower? The backspacing of the spare wheel differs from the primary wheels by a half inch, but the offset is the same at 12 mm positive. There are no clearance issues with the fender well, drum, or with suspension travel with the spare installed.

While I'm sure it would be recommended to use an exact replacement wheel, money is tight and my options limited. I'd just like to know if running the spare as the permanent replacement despite the difference in width will be safe and without negative effect on the truck.

Also, if there aren't any foreseeable potential problems using the spare wheel, would there be a recommendation for whether to run it on the rear axle or on the front of the truck? The truck is an automatic 2WD with 4-wheel ABS and a limited-slip differential.

Thanks for any info/advice you might offer.