If the plug is truly oil fouling, then yes, a hotter plug or a non-fouler will help.
But any plug will foul if the cylinder is not firing for any reason. Could be weak spark, low compression, cracked head or leaking head gasket, or improper mixture.
Once a cylinder has been run misfiring for an extended time, the cylinder will be sooted up and oily. It may quickly foul a new plug until it cleans itself up after a while of successfully firing.
Be sure there is good spark at the plug end of the plug wire.
Check the compression, adjust the valves if that hasn't been done lately, and inspect the valve train while there. Look for broken springs, valves not fully opening (flat cam), bent pushrods.
Be sure the thermostat is working properly, and the engine is coming up to operating temperature.
Carefully check for vacuum leaks, especially since this is a cold weather problem. Look for a manifold gasket leak since it seems to favor one cylinder.
Back to the original question, yes there are hotter plugs. The 11 is the heat range, Higher numbers run hotter, 11 is mid-range, you can go up to a 12, 14, or 16. If you determine the problem is oil fouling, you can use a non-fouler, it is a threaded spacer that moves the plug out of the splash zone and causes the plug to run much hotter. Should be used only as a last resort, and you might want to go back down to a colder plug for that one.
Have a look at this chart, see what best matches the results you are seeing.
Plug Chart