I'm going to work through and see if I can set up a viable 10 level build using Martial Rogue and Arcane Stunt for the Swashbuckler. That should allow me enough feats to pick up some ranged ones as well. It will get rid of the reliance on SA, because knowing the DM there will be plenty once we hit lvl 6+ that are immune to SA.
What are you going to replace sneak attack with for damage? It is very difficult to get enough damage to be relevant, and sneak attack is one of the best ways, especially to get damage that applies to both weapons. There are some others, but they all require casting, new mechanics, don't work well with TWF, or some combination of the three: charging requires pounce, Power Attack, Leap Attack, Shock Trooper, and a two-handed weapon. I suspect it would be better to focus on ways to avoid sneak attack immunity.
So with that in mind would it be better to multi the Martial Rogue with something else? Lose Swashbuckler. Pick up Over-sized Two Weapon Fighting?
Mix the Martial Rogue with say Barbarian for rage? Or ?
Nothing is really set in stone other than I'd like to stick with some rogue abilities and use TWF if it's going to be beneficial to the group. If it's better to do Martial Rogue 1 level and go full on fighter, or ranger or something after that I am open to the idea.
What are you going to do with the feats from martial rogue? Again, where is your damage coming from if you give up sneak attack?
Barbarian is a good dip for many melee characters, especially with ACFs. A 2-level ranger dip for TWF and a swashbuckler dip for Weapon Finesse are also plausible, but what feats do you want that makes the dip worthwhile?
Keep in mind that a 3-level swashbuckler dip with Daring Outlaw is not a very effective use of class levels. Compared to taking three levels of rogue and not spending the feat, you go down skill points because swashbuckler only gets 4 + Int and delay the rogue specials, all for +Int to damage and being sometimes 1 ahead on BAB. Even with your ridiculous stats, you're not going to get more than +3 to damage and the opportunity to spend 4k and a body slot later to get +1 more, then 12k, then 20k. You have to have massive amounts of money before buying Int items for damage becomes efficient, and the only other thing they'll do for you are boost a couple of skills. Compare Weapon Specialization, which gives +2 damage and sucks.
Does the Dread Pirate prestige have any value? I will be starting out with a boat as apparently we need one and the DM decided I'd have the boat while the other guys will have houses/keeps in various towns.
It does but not for your concept. The good ability that dread pirate gets is the honorable version's rally the crew, and you want inspire courage before you go into dread pirate if you're going that direction. Dishonorable dread pirate is a trap.
Don't even think about taking Oversized TWF. Going up from a light weapon to a 1h weapon is usually only an average damage increase of 1. Not even Weapon Specialization is that bad. Note that it doesn't let you take the off-hand's 1/2x strength mod to damage and up it to 1x. Here's the reference for off-hand attacks only adding 1/2x strength to damage. If it did, then it'd be worth it.
That's actually one of the "balancing" factors for TWF versus 2h weapons. 2h weapons get 1.5x strength mod to damage, while TWF has 1x and .5x, which adds up to 1.5x. However, the Exotic Weapon Master PrC ups the damage from strength to 2x for certain weapons, so a PrC might be in order to get a TWF build's off hand up to 1x. Alternately a sufficiently "intensive" feat chain might do it.
Like Jackingreen said, Oversized TWF is not good. The only reason ever to take it is for Power Attack, but if you're doing that, why not just use a two-handed weapon in the first place?
Exotic weapon master's uncanny blow only works with an exotic one-handed weapon you hold in two hands, so it doesn't apply here.