I hope I'm not too late to be of any use, but I think it's possible to do exactly this.
First off, let me say that I don't think this is a dumb idea, I would actually agree with you, except that SE gimped the difficulty of levelling to the point that you can get level 75 solo on any job quickly with little effort.
My idea of how to start:
That's right, go grab yourself a fishing pole and little worms from the guild in Port Windurst, if you use your Adventurer's Coupon you'll have 50 gil, allowing you to buy a little worm. Doesn't sound like much, until you start looking at what equipment you started the game with. Sell it. Sell anything you can, to NPC's or the auction house. Somehow, you need to come up with another 29 gil, so you can buy a Willow fishing rod. Once you have that, go fish. Don't fish in the ocean, you're liable to break your rod and lose your bait, and have to start over, go fish in Woods or Waters, where you can possibly fish up some moat carp (or more likely crayfish). Should you get even a crayfish, you'll find you can sell it for more than the cost of the little worm. It's a slow start, but you'll find that you'll soon be rolling in dough. Try to buy yourself a Halcyon rod as early as possible to help out with avoiding breaks. Once you have a sufficient supply of gil, you can freely move on to the other crafts, no social interaction required, no grinding required.