Tire rotation 2 axle

I would avoid rotating at all. Much easier to spot a tire or alignment issue if you know the tire has been in the same position. All tires should wear the same and flat across the tread. The power, braking, steering, alignment, and cornering forces are virtually the same in all positions. Not like the tow vehicle where all is different.

As said above you will not get more life out of the tires for rotating the spare in with the others. Do carry a compressor to air up the spare if placed in service or cover for a slow leak until you can get in for repair.