How much transparency do you guys want in character design? I can give you full control of stat and charm selection, minus the basic mortal package, or I can build my own based on limited voting.
I'm not the most skilled build creator, but I do alright if I really sit down and work it out.
Honestly the only area that would probably be particularly meaningfully divisive with an infernal is charms. Being neither ability based nor attribute based, favored abilities/etc aren't really super-important (We shouldn't pick randomly but the 1xp discount on each ability dot and quick training times aren't going to be changing the world with 2.5 character gen.) and most of the points would be mortal template.
As for charms, there are a few core charms we'd be crazy not to pick depending on favored yozi (IE: Kimbery better have Mother Sea Mastery with this setting, Adorjan would usually go Wind-Borne Stride at least once, etc) so they could be easily assigned. We'll probably want at least one excellency, but that could be either caste or favored. (With all the repurchases and the branch charms we'd want we're shooting ourself in the foot if we go with a non-favored one sadly.)
So something like "Witness to Darkness, Mother Sea Mastery pre-assigned, and (Other charm you definitely think we should have) are assigned"
"Choose ED or Kimbery Excellency(X2 for essence repurchases), then 5 more charms." would get my vote.
That seems like it would give a nice balance of player choice and not having 80 million things to argue over or making a ton of work for the GM to generate options.
As for sailing a ship in sand we'd either need an artifact ship or probably out of caste charms. Solars are good at ships (and therefore the sea) and infernals are good at becoming the sea ( and therefore can sail pretty well)
Getting to Malfeas, if we want to go that route, and it's possible for us, is a bit tricky. Hell-Walker Technique would do it for us, allowing us to simply walk there whenever, but getting back to the Grand Line instead of Creation would be hard without a few more Cecelyne charms.
(Hell-Walker technique's prerequisites are both pretty nifty if we're ever going to be in places that suck to be in, like a lot of the grand-line. Still a 3 charm dip into Cecelyne isn't particularly cheap or easy at chargen and would probably mean passing on something amazing for now. Getting back out to the same place requires we have Dune-Drowned Oasis, which would pretty much let us go anywhere we set up in 10 days tops, but is another 2 charms, essence 4 and cult 2.)
Finding a secret entrance to Malfeas would be a good way to get in and out, but might have issues there since that's basically whatever the ST wants to give us. There are also some artifact keys we could get if we want to build to be able to make artifacts (unlikely as hell).