Currently it is not possible to disable link preview tool tips -- changing SKToolTipWidth and SKToolTipHeight to 0 causes Skim to crash when the mouse is over a link. A new hidden boolean preference, say SKDisablePreviewToolTips, to complement SKDisableTableToolTips, would solve this, for me, distraction.
Sorry, we won't do this. We won't add (hidden) prefs to infinity.