There's no magic solution.
Penetrating sprays do not work instantly. If you spray it and the bolt instantly turns or the mount instantly pops out of the socket, it was going to come out anyway. The spray didn't hurt but it also didn't help.
WD-40 is a poor penetrating spray. Use their special-purpose penetrating lube, or PB blaster, or Kroil, or Liquid Wrench, or a mixture of automatic transmission fluid and acetone. Even then it will take at least 24 hours to do any good at all, probably longer.
The quickest solution is "heat and beat." You need an oxy-acetylene torch to provide the heat, or 3-4 propane torches all at once. A single propane torch cannot put out the BTUs to heat the outer sleeve to a high enough temperature. It will get too hot to touch, but not hot enough to expand because the heat dissipates faster than the torch can replenish it.
Putting 10-ply tires on half ton trucks since aught-four.