Who said there are no boots on the ground? There are plenty of advisors on the ground.
'The Kurds are the best bet, but supplying them is a no no because they are marginalised by Turkey, a NATO member'
Except for the fact that Canadian forces have been helping them on the ground.
Indeed get on with it ! Maybe you should look into the treatment of the American woman who had her finger nails removed and was tortured and raped in the hands of ISIS if you feel that justification for war is 'thin' .
Wage an air campaign - remove the ability to regroup day and night -make movement impossible and watch them splinter as you degrade their ability to function. When that is achieved -let the ground forces finish them.