Here's a pretty nifty macro I cooked up.
When you click it, it will first attempt to equip your fishing gear (Hat and Kalu'ak pole in my case).
The next click will use your Weather Beaten Fishing Hat to put the +75 lure on your Fishing Pole.
Any subsequent clicks will simply cast your fishing line as normal (until your fishing lure runs out, then it will refresh it!)
#showtooltip Fishing
/script UIErrorsFrame:UnregisterEvent("UI_ERROR_MESSAGE");
/equip Mastercraft Kalu'ak Fishing Pole
/equip Weather-Beaten Fishing Hat
/use Weather-Beaten Fishing Hat
/script UIErrorsFrame:RegisterEvent("UI_ERROR_MESSAGE");
/use Fishing
Enjoy!!