Once the trip to Sky Island was decided, Xie Wen had everyone, mainly the two research cats, start preparing.
After all, Luffy had already blundered through most of the pitfalls in the manga. Although he and the cats were capable of dealing with them directly, there was no need to put themselves through that extra suffering.
First, since they would have to pass through thick Sea Clouds on the way up, which could drown people just like seawater, an Oxygen Tank for everyone was essential. For Devil Fruit Users like Klee Meow and Robin, they had better also prepare Diving Suits that sealed off their entire bodies, in case they accidentally fell overboard.
Second, although the Toot Toot Forward was built from Treasure Tree Adam and was far sturdier than Luffy's patched-up Going Merry, that did not stop them from reinforcing her further. And Xie Wen remembered that updrafts accompanied the Knock Up Stream, so they could add a few extra sails to the Toot Toot Forward to improve her climbing ability.
Besides, the Going Merry had been fitted with wings in the manga. Although Xie Wen doubted they would be much use, he would still have them fitted to the Toot Toot Forward. Transmigrators were supposed to follow the protagonist's lead when feeling their way forward, after all. There was no need to go against the plot over such a minor issue.
Last came the matter of safety...
With Xie Wen's foreknowledge and Klee Meow's good luck, there was basically little chance of anything going wrong on their way to Sky Island. Still, better safe than sorry. If they failed, they would fall from ten thousand meters in the air.
There was no particular need to worry about anyone's life, since they had Germa's Raid Suits. Even Meowrah and