The hardest part to skipping the Fishing Rod is not skipping the item itself (since it's simply a matter of doing the Day 1 & 2 skip), but rather beating the game without it. In a normal playthrough, the only use for the Rod is to use it to catch reekfish to get the reekfish scent, which allows you to find the path up Snowpeak. But, when the Map Glitch allowed for early Snowpeak, and the Zora's Armor became skippable, the Fishing Rod became a required item again for obtaining waterbombs so to enter Lakebed Temple early.
How To Edit
Discovered by logitechSDAZ
To do this, take out the sword, hold L (sometimes helps get a better camera angle), and press B a split second before you get the rupee. The timing is hard. If you swing your sword too soon, you'll get the rupee in midair and the animation won't happen to where you can dive out of bounds. However, this is easier than standing on the very edge, not swinging your sword, and hoping the dive works.
There are 14 small jars by Fyer's cannon, and it is random which jar will have the blue rupee. And even worse, at least 50% of the time, none of the jars will have a blue rupee. In a speedrun, you'd have to hope the 1st jar you grab has a blue rupee. So the odds are really bad.