I've had dry mouth forever from a med (vaping didn't really necessarily worsen it, but that would be kind of a feat.) Dry mouth lozenges (biotene and other makers) do somewhat help, if you can find one that you can actually tolerate the taste of, and I actually think most (sugar free might be best) hard candy is just going to start saliva production in your mouth, chewing gum would give you the same general effect.
Biotene mouthwash BEFORE bed can be useful, I'm not sure how useful it is during the day (maybe a bit) but it does kind of wear off as you eat and drink etc. It MAY prevent waking up in the middle of the night with cotton mouth if you use it before bed. Etc.
Drinks like chamomile tea with honey and lemon in them can also sometimes help, the lemon is kind of mildly astringent and takes away that "ick" feeling and honey coats your mouth and throat (to a moderate degree, I guess) and chamomile well if you are stepping down your nic, I am of the personal opinion that chamomile tea is more calming than most OTC products have any right to be.. Your mileage may vary.
You can increase the nic in your "step down" juices if you want to use them. Either go to the DIY forum and./or find a good nic calculator and start inputting your amounts of juice and the strength of whatever nic you get, and you should be good to go. You may just want to wait, honestly, if you do plan on stepping down but slower, they should be perfectly fine if stored in a cool dark place for a while. But, if you want to use them immediately, you'd need to acquire a (fairly small amount) of nic in whatever way you acquire it and just doctor your mixes a bit. Good luck,
Anna