For roadside emergency use, don't sweat it. Use the spare to get to the nearest tire shop, get the primary tire fixed, put it back on, and be on your way.
This whole deal of having to have left-hand threaded lug nuts on the left wheels or else they will come flying off is no longer relevant. Every car, truck, and trailer that rolls off an assembly line these days has all right-handed lug nuts. Clearly they figured out how to keep the lug nuts tight regardless of which way the wheel turns.
If it were such a chronic problem, the federal government would have mandated left-hand threaded lug nuts on the left side of the vehicle decades ago.