Sorry...I couldn't find any clone recipes online and I never tasted Skull & Crossbones before. But in consolation, here's a nice recipe for sup tulang http://thinkingmomsrevolution.com/malaysia...yle-bone-broth/

There's TFA Jamaican Rum if you're gonna go DIY. Vaperstuff has em. Maybe Flavorist as well. FA Jamaican Rum is more delish tho but impossible to find locally.

http://www.lelong.com.my/merchant/TakeItGlobal.htm has white and jamaican rum. If you don't see it listed in lelong, just message the seller, Mr Heah.

To my tastebuds, the white rum is ok. Have yet to test the jamaican rum.
The brandy is well worth using.
The whiskey and bourbon are very similar in taste.

All are Ungerer flavors.

Who knows? It could even be the same person who was asking in /k about being bipolar!    Endless possibilities.... 
Actually your question had intrigued me...been doing some thinking about it. The company seems to have a pirates of the caribbean theme, so it's most probably be jamaican rum used. Bear in mind I've yet to taste it and the following is merely a guesstimate based on stated main flavors and impressions of several reviewers. Maybe u can try making a trial 5ml bottle of

Acetyl pyrazine 0.5%
Butter, Capella 1.5%
Butter cream, Capella 2.5%
Yellow cake, FlavorWest 3%
Jamaican rum, whichever brand u come across 2.5%
Vanilla bean ice cream, TFA 3.5%
Brown sugar TFA 1.5%

Vids of the cloud production make me think it's probably 50/50 pg/vg. If you taste any spices in the rum of the original, do let me know.

For myself, I'll always taste every juice when freshly made, even tho it requires steeping. This lets me know how the recipe will go as it matures. It also lets me know the interactions of the various flavors in those proportions from day 1...that's valuable info. Also, generally speaking if an experimental mix tastes like crap on the first day, chances are slim that it will taste better later on.

With that having been said, judging from your ingredients, your mix should turn out to be rather decent! Am glad you went easy on the ethyl maltol...it's a great flavor muter. If you want some gentle smoothing of your mix and a touch of sweetening, consider TFA Marshmallow instead of EM...it's a better mixer. But if you taste cotton candy in the original juice, then EM's the way to go. Should you detect a touch of saltiness in the original, then you may wish to try adding 4 to 4.5% saline while upping the other flavors to above 22% in total (otherwise it'll just taste weak due to the dilution by the saline).

About PG/VG ratios
PG is the flavor carrier..so the more PG you use, the more flavor you get. Want more clouds, up the VG %. That's the general way things go.

However in my continuous musings on why some import juices taste so much better, one factor I've been cracking my head on is "mouth-feel". I believe mouth-feel also contributes to our perception of flavor. Imagine if you will, 2 same-flavor juices (not necessarily having the same percentage of flavors)...one with thinner vapor production and one with much thicker vapor. I've made high VG versions of 50-50 juices and I prefer the former....gobs of thick rich vapor in my mouth. Am currently experimenting with VG-based flavorings and additives. So far the initial results of several juices have been most gratifying (2 thumbs up from my usual victims) 
OK..good to know that. Now I'm wondering how it'll taste when a spiced jamaican rum is used instead! Aah infinite possibilities...

Apple Pie Vanilla Bean Ice Cream with Caramel (taste like Gambit)
Strawberry Custard (taste like Unicorn Milk)

Apple Pie Vanilla Bean Ice Cream with Caramel (taste like Gambit):

Acetyl Pyrazine 5% - 4%
Apple Pie (TPA) 11%
DX Caramel (Original) (TPA) 1.65%
Caramel Candy (TPA) 1.65%
Cotton Candy (TPA) 2.2%
Pie Crust (TPA) 2.2%
Vanilla Bean Ice Cream (TPA) 5.5%
Vanilla Custard v2 (CAP) 0.55%
Whipped Cream (TPA)  2.2%

50PG/50VG blend

Strawberry Custard (taste like Unicorn Milk):

Butter Cream (FW) 1.5%
Graham Cracker (TPA) 0.5%
New York Cheesecake (CAP) 0.5%
Sweet Cream (CAP) 1.5%
Sweet Strawberry (CAP) 8.5%
Vanilla Bean Ice Cream (TPA) 1%
Vanilla Custard v2 (CAP) 3%

25PG/75VG blend