You might consider the better boat mod if you make boats non-craftable. At least then boats break into boats and are far less likely to accidentally break due to desync. Otherwise somebody will visit an island, think the boat is going to safely go one way, then jump out only to see the boat do a 180 and then ram into the island, turning itself into kindling. Which is very annoying even when you can craft boats.
Of course if somebody boats out to an island to clear a cavern and then dies out there they're still royally screwed since they won't have a boat to go back to get their stuff. They can build a glider though and carry a few stacks of blocks and then just nerdpole glider hop from island to island, I suppose. That's probably better than a boat anyhow, as long as it doesn't turn to night mid-flight. One related note is that you can get lily-pads with an mfr fisher and a lily pad is placeable on water so you'd be able to build a sleeping platform anywhere in the water if you had to. Angel blocks work too I suppose although feathers are quite rare in skyblock since the only source in 1.5.0 is zombie jockeys. There are ways to kill the baby zombie and grab the chicken. I also have a few eggs from somewhere which could be the start of a chicken farm so maybe feathers aren't as rare as I thought they were.
I did consider making a more difficult recipe to prolong its use after I'd added the 2 new quests that award the boat and if the new system proves to be too difficult I'll revisit it again. The way it stands now you get a boat from each quest and as the earlier quest is repeatable and only requires handing in crops that are actually much easier to grow in the skyworld than they were in the land based worlds, it shouldn't take too long to get a few boats before heading off to explore. So travelling somewhere by boat won't be as difficult if players wait until they have 2 or more boats to take with them when exploring the ocean world. I've just been doing another run through in the newest skyworld and am amazed that I'll have the first crop quests finished before I get my ores grown. the plains biome seems to churn them out at a fast pace. I doubt I'll even need the watering can for this world.
I actually tried the better boat mod way back in 1.7.3 beta. It took some trial and error to get a boat to have just the right amount of strength back then, but I did enjoy the mod. Forgot all about it for this pack as it wasn't needed up until we switched the then prototype skyworld from a void to an ocean. Thanks for reminding me about it, I'll revisit it and may include it in a future update if its compatible and worth including just for the one world. considering its now a requirement to go out exploring the many islands dotted around the environment, I may need to do some serious thinking about it. Especially now that they're all generated randomly.
Lily pads have been introduced in the new skyworld as a randomly spawning ruin along with water gardens. Th gardens are in the 1.5.0 version by default as ocean biomes spawn them naturally.
As for feathers, I doubt anyone will want to continue playing 1.5.0 after 1.5.2 is released, but then again, who knows...........