I'm currently trying this LTW but my sim is a mermaid, I put the sim I made for great explorer in the game, cheated the islands and got the happiness points, made her a mermaid and changed her LTW then saved her household to the family bin as you cannot save mermaids to the sim bin, then started a new game.
I admit it is an advantage having level 10 diving from the start, you can go straight to Pearls Deep and get the better fish such as eels, end of week two and she is over half way there with a boyfriend but he's pretty much the extent of her social life, I did this as much to try out mermaids as the LTW but I can imagine it will be much slower going if she wasn't. Being able to stay in the water all day helps too, she can eat kelp underwater so hunger isn't a problem, it's just when she gets tired she tends to leave or it gets very late and the fish stop spawning.
I'll have to try it without being a mermaid sometime to see how much harder it is.