Ive used oakwood in the past too, its pretty spot on. The thing about using real wood is each different type imparts different but subtle flavors. Sure we can do this with flavorings but it is kind of interesting to see. Different level of char can increase or decrease certain flavors too. I would probably stick with light charing in the future, while medium was very nice it is also too much to vape all the time.
Wine making sites are a great place to start for information on the flavors different types of oak impart on beverages.
I wonder if you could use Jack Daniels wood chips or chunks that I use for smoking meats? If so, it might add great flavor for a cocktail and/or tobacco juice. Maybe a custard too.
I am sure it would work fine and transfer some of the wood essence to your mix, although a lot of the barrel steeping involves priming the barrel with a alcohol flavor you want. I filled the barrel with dark rum let it sit to infuse into the barrel wood then emptied and added my mix to set and steep for at least 2 weeks. then re bottled the mix into dark glass and let it steep months. Custard mix would be absolutely wonderful I would bet.
It is a pretty straight forward process. Nothing more complicated than buying a barrel, follow the manufactures suggested sealing process (very simple, fill with distilled water let it sit and rotate now and then until seeping stops, then empty) and then adding your mixture (minus nicotine I would suggest) let it sit for at least 2 weeks then re-bottle and steep for whatever you feel is necessary (recipe dependent)
